Official Paper

KVS PGT Maths Official Paper (Held On: 18 Feb, 2023 Shift 2) (Previous Year Paper)

180 questions · 180 minutes · with answers · free

Language Proficiency (20 questions)

1

Rearrange the parts in correct order to make a meaningful sentence

(a) and broke its window pane 

(b) threw stones at it

(c) the urchins

(d) when the car passed by,

  1. ((a))

     (c) (d) (b) (a)

  2. ((b))

     (d) (c) (b) (a)

  3. ((c))

     (b) (a) (c) (d)

  4. ((d))

     (a) (b) (c) (d)

Show Answer
Answer: ((b))

 (d) (c) (b) (a)

The correct answer is Option (2) i.e. (d) (c) (b) (a)

Key Points

  • The sentence must begin by setting the context, which is the time of the action. This is provided by the dependent clause part (d): "when the car passed by,".
  • Following the introductory clause, the sentence must introduce the subject of the action, which is part (c): "the urchins".
  • Next, the first action performed by the subject is stated, which is part (b): "threw stones at it".
  • Finally, the result of the action is stated, which is connected by the conjunction "and" in part (a): "and broke its window pane".

Therefore, the correct sequence is (d) (c) (b) (a).

Additional Information

  • Option 1 (c) (d) (b) (a): This sequence places the subject first ("the urchins when the car passed by, threw stones at it..."), which creates an awkward and grammatically incorrect structure by separating the subject from its verb with an entire clause.
  • Option 3 (b) (a) (c) (d): This sequence starts with the verb ("threw stones at it and broke its window pane the urchins when the car passed by,"), which is completely nonsensical.
  • Option 4 (a) (b) (c) (d): This sequence starts with the second verb ("and broke its window pane threw stones at it the urchins when the car passed by,"), making the sentence incoherent.

Coherent sentence after rearrangement: "When the car passed by, the urchins threw stones at it and broke its window pane."

2

Change the following sentence from Active Voice to Passive Voice.

Some local residents were helping the wounded soldier.

  1. ((a))

    Some local residents were being helped by the Wounded soldier

  2. ((b))

    The wounded soldier was helped by some local residents

  3. ((c))

    The wounded soldier was being helped by some local residents

  4. ((d))

    Help was being given to the wounded soldier by some local residents.

Show Answer
Answer: ((c))

The wounded soldier was being helped by some local residents

The correct answer is Option 3.

 

Key Points

  • Passive voice structure: The object of the active voice sentence becomes the subject of the passive voice sentence.
  • In the active voice, the sentence is: "Some local residents were helping the wounded soldier."
  • To convert to passive voice: Place the object "the wounded soldier" at the beginning.
  • Change the active verb form "were helping" to "was being helped" (past continuous passive).
  • Add the preposition "by" followed by the original subject "some local residents."

Therefore, the correct answer is Option 3.

 

Correct Sentence: "The wounded soldier was being helped by some local residents."

 

Additional Information

  • Option 1: "Some local residents were being helped by the wounded soldier." – Incorrect meaning (reverses subject and object).
  • Option 2: "The wounded soldier was helped by some local residents." – Incorrect tense (simple past instead of past continuous).
  • Option 4: "Help was being given to the wounded soldier by some local residents." – Correct meaning but awkward phrasing.
3

Fill in the blank with the correct preposition.

They ran _________ the thief who had stolen their belongings.

  1. ((a))

    from

  2. ((b))

    after

  3. ((c))

    with

  4. ((d))

    in

Show Answer
Answer: ((b))

after

The correct answer is 'after'.

 

Key Points

  • The preposition "after" is used to indicate pursuit or chasing.
  • In this sentence, the people are chasing the thief who stole their belongings, making "after" the correct choice.
  • Options 1, 3, and 4 are incorrect because they do not fit the context of chasing.

Therefore, the correct answer is Option 2.

 

Complete Sentence: "They ran after the thief who had stolen their belongings."

 

Additional Information

  • Option 1: "from" is incorrect because it indicates separation or source, not pursuit.
  • Option 3: "with" is incorrect because it indicates accompaniment, not chasing.
  • Option 4: "in" is incorrect because it indicates location or position, not pursuit.
4

Choose the correct tense form from the given options.

This was the first time the mighty king had lost a battle.

  1. ((a))

    Past Indefinite

  2. ((b))

    Past Continuous

  3. ((c))

    Past Perfect

  4. ((d))

    Past Perfect Continuous

Show Answer
Answer: ((c))

Past Perfect

The correct answer is Option 3 i.e. 'Past Perfect'.

Key Points

  • The verb phrase “had lost” is in the Past Perfect tense.
  • Past Perfect is used to show that an action was completed before another action or point in the past.
  • In the sentence, “This was the first time” is the reference point in the past, and “the mighty king had lost a battle” happened before that.
  • Therefore, the tense form used in the sentence is Past Perfect.

Therefore, the correct answer is- Option 3.

Additional Information

  • Option 1 (Past Indefinite): Uses the simple past tense such as “lost,” which does not indicate the order of two past events.
  • Option 2 (Past Continuous): Refers to an ongoing action in the past (e.g., “was losing”).
  • Option 4 (Past Perfect Continuous): Describes an action that was ongoing in the past up to a certain point (e.g., “had been losing”).
5

Change the following sentence from Direct Speech into Indirect Speech.

The young man said to his parents, 'You will have to adjust to the changing times'.

  1. ((a))

    That they would have to adjust to the changing times the young man told his parents.

  2. ((b))

     The young man told his parents that they must adjust to the changing times.

  3. ((c))

    The young man told his parents that they would have to adjust to the changing times.

  4. ((d))

    The young man told his parents that he (the young man) would have to adjust to the changing times.

Show Answer
Answer: ((c))

The young man told his parents that they would have to adjust to the changing times.

The correct answer is Option 3.

 

Key Points

  • Indirect Speech: The young man told his parents that they would have to adjust to the changing times.
  • Key Conversions:
  • Pronoun Change:
  • "You" (addressing parents) becomes "they" in indirect speech.
  • Modal Verb Shift:
  • "Will have to" in direct speech changes to "would have to" in indirect speech to match sequence of tenses.
  • Reporting Verb:
  • "said to" is replaced by "told" to indicate whom the statement is addressed to.
  • Punctuation and Format:
  • Indirect speech does not use quotation marks.
  • The sentence structure changes from direct address to reported statement.

Therefore, the correct answer is Option 3.

 

Correct Sentence: "The young man told his parents that they would have to adjust to the changing times."

 

Additional Information

  • Option 1: Poor word order and clarity make it incorrect.
  • The subject and reporting clause are not properly structured.
  • Option 2: Changes the modal from "will have to" to "must," altering the original meaning.
  • Does not accurately reflect the original speech.
  • Option 4: Incorrectly shifts the subject to "he (the young man)," which changes the meaning.
  • The statement is about the parents, not the young man himself.
6

Identify the part which has an error in it.

From this place, / Meerut is / over ten miles / the shortest route

           (1)                 (2)               (3)                       (4)

  1. ((a))

    From this place

  2. ((b))

    Meerut is

  3. ((c))

    over ten miles

  4. ((d))

    the shortest route

Show Answer
Answer: ((d))

the shortest route

The correct answer is Option 4.

 

Key Points

  • The error in the sentence lies in the phrase "the shortest route" in part 4.
  • The correct preposition to use here is "by" instead of "the" to indicate the route being referred to.
  • The phrase should be "by the shortest route" to maintain grammatical accuracy and clarity.
  • Thus, the error is located in part 4 of the sentence.

Therefore, the correct answer is Option 4.

 

Correct Sentence: "From this place, Meerut is over ten miles by the shortest route."

 

Additional Information

  • Option 1: "From this place," – This part of the sentence is grammatically correct and does not require any changes.
  • Option 2: "Meerut is" – This part of the sentence is grammatically correct and does not require any changes.
  • Option 3: "over ten miles" – This part of the sentence is grammatically correct and does not require any changes.
7

Choose the word nearest in meaning to the given word.

ABETMENT

  1. ((a))

    enmity

  2. ((b))

    assistance

  3. ((c))

    revenge

  4. ((d))

    reaction

Show Answer
Answer: ((b))

assistance

The correct answer is: Option 2 (Assistance).

Key Points

  • The word "Abetment" refers to the act of encouraging, supporting, or assisting someone to do something, especially something wrong or illegal. (उकसाना, सहयोग)
  • Example: The abetment of criminal activities can lead to legal consequences.
  • "Assistance" means providing help or support to someone to achieve something. (मदद, सहायक)
  • Example: The government provided financial assistance to the flood victims.
  • Hence, we can infer that "abetment" is closest in meaning to "assistance."

Therefore, the correct answer is: Option 2 (Assistance).

Additional Information

Here are the other options explained along with their Hindi meanings and example sentences:

  • Enmity (दुश्मनी): The state of being actively opposed or hostile to someone or something.
  • Example: The two families have harbored enmity for decades.
  • Revenge (बदला): The action of inflicting harm or punishment on someone for a wrong suffered at their hands.
  • Example: He sought revenge for the injustice done to him.
  • Reaction (प्रतिक्रिया): A response to a situation, event, or stimulus.
  • Example: Her reaction to the surprise party was priceless.
8

Choose the word opposite in meaning to the given word.

SLOTHFUL

  1. ((a))

    healthy

  2. ((b))

    active

  3. ((c))

    intelligent

  4. ((d))

    indolent

Show Answer
Answer: ((b))

active

The correct answer is: Option 2 i.e. Active.

Key Points

  • The word "Slothful" refers to being lazy or unwilling to work or make an effort. (आलसी)
  • Example: He was too slothful to get out of bed and start working on his assignments.
  • "Active" refers to being energetic, dynamic, and always ready to engage in physical or mental activity. (सक्रिय)
  • Example: She is an active participant in all the community events and activities.
  • Hence, the opposite of 'slothful' is 'active'.

Therefore, the correct answer is: Option 2 i.e. Active.

Additional Information

Here are the other options explained along with their Hindi meanings and example sentences:

  • Healthy (स्वस्थ): Being in good physical or mental condition.
  • Example: Regular exercise and a balanced diet help in maintaining a healthy lifestyle.
  • Intelligent (बुद्धिमान): Having or showing intelligence, especially of a high level.
  • Example: She is an intelligent student who always tops her class.
  • Indolent (आलसी): Wanting to avoid activity or exertion; lazy.
  • Example: His indolent behaviour often delays the completion of important tasks.
9

Identify the part of speech of the given word.

Moderate fasting is good for health, so testify the medical experts.

  1. ((a))

    Pronoun

  2. ((b))

    Verb

  3. ((c))

    Noun

  4. ((d))

    Conjunction

Show Answer
Answer: ((c))

Noun

The correct answer is Option 3 i.e 'Noun'.

Key Points

  • The underlined word "fasting" refers to the act of abstaining from food, which is being used as the subject of the sentence.
  • Although "fasting" originates from the verb "fast," here it functions as a gerund, which is treated as a noun.
  • Since it names an activity rather than showing an action, its part of speech in this context is noun.

Therefore, the correct answer is- Option 3.

Additional Information

  • Pronoun: A pronoun replaces a noun (he, she, it). "Fasting" does not replace a noun, so this is incorrect.
  • Verb: A verb shows action. While "fast" is a verb, in this sentence "fasting" is not performing an action but naming one.
  • Conjunction: A conjunction joins words or clauses (and, but, so). "Fasting" does not serve this role.
10

Have you finished reading the book

What punctuation mark should be placed at the end of the sentence?

  1. ((a))

    Full stop

  2. ((b))

    Mark of interogation

  3. ((c))

    Semi-colon

  4. ((d))

    Mark of Exclamation

Show Answer
Answer: ((b))

Mark of interogation

The correct answer is Option 2.

 

Key Points

  • The sentence is a question, so it should end with a question mark, also known as a mark of interrogation.
  • A question mark (?) is used to indicate that a question is being asked.
  • Other options like a full stop, semi-colon, or exclamation mark would not be appropriate for a question.

Therefore, the correct answer is Option 2.

 

Correct Sentence: "Have you finished reading the book?"

 

Additional Information

  • Option 1: "Full stop" – A full stop is used at the end of a declarative sentence, not a question.
  • Option 3: "Semi-colon" – A semi-colon is used to connect closely related independent clauses, not at the end of a question.
  • Option 4: "Mark of Exclamation" – An exclamation mark is used to express strong emotion, not to indicate a question.
  • Option 2: "Mark of Interrogation" – This is the correct option for indicating a question.
11

निम्नलिखित गद्यांश को ध्यानपूर्वक पढ़कर उसपर आधारित प्रश्न का सही उत्तर दीजिए :

             वर्तमान समय में विज्ञापन का विशेष महत्व है। उपभोक्ता वर्ग के एक बहुत बड़े वर्ग में किसी उत्पाद को खरीदने से पहले विज्ञापन द्वारा उसके बारे में जानकारी प्राप्त करने की प्रवृत्ति रही है। विज्ञापन से उत्पाद को उसके उपयुक्त उपभोक्ता तक पहुँचाने में सहायता मिलती है। भारत ही नहीं संपूर्ण विश्व में विज्ञापन एजेंसियों का बहुत बड़ा तंत्र सक्रिय है। विज्ञापन एजेंसियों के कार्यालय अधिकतर महानगरों में हैं। दूर दराज के क्षेत्रों में भी रेडियो, टेलीविज़न और समाचार-पत्रों के माध्यम से विज्ञापन पहुँच रहे हैं।

उपभोक्ता वर्ग में विज्ञापन से संबद्ध किस तरह की प्रवृत्ति रही है?

  1. ((a))

    उत्पाद को खरीदने से पहले उसका विज्ञापन देखने की

  2. ((b))

    विज्ञापन द्वारा उसके बारे में जानकारी प्राप्त करने की

  3. ((c))

    विज्ञानप द्वारा खरीदने की

  4. ((d))

    विज्ञापन देखने और उनका आनंद लेने की

Show Answer
Answer: ((b))

विज्ञापन द्वारा उसके बारे में जानकारी प्राप्त करने की

सही उत्तर है- विज्ञापन द्वारा उसके बारे में जानकारी प्राप्त करने की

Key Pointsगद्यांश के अनुसार-

  • “उपभोक्ता वर्ग के एक बहुत बड़े वर्ग में किसी उत्पाद को खरीदने से पहले विज्ञापन द्वारा उसके बारे में जानकारी प्राप्त करने की प्रवृत्ति रही है।”
12

निम्नलिखित गद्यांश को ध्यानपूर्वक पढ़कर उसपर आधारित प्रश्न का सही उत्तर दीजिए :

       वर्तमान समय में विज्ञापन का विशेष महत्व है। उपभोक्ता वर्ग के एक बहुत बड़े वर्ग में किसी उत्पाद को खरीदने से पहले विज्ञापन द्वारा उसके बारे में जानकारी प्राप्त करने की प्रवृत्ति रही है। विज्ञापन से उत्पाद को उसके उपयुक्त उपभोक्ता तक पहुँचाने में सहायता मिलती है। भारत ही नहीं संपूर्ण विश्व में विज्ञापन एजेंसियों का बहुत बड़ा तंत्र सक्रिय है। विज्ञापन एजेंसियों के कार्यालय अधिकतर महानगरों में हैं। दूर दराज के क्षेत्रों में भी रेडियो, टेलीविज़न और समाचार पत्रों के माध्यम से विज्ञापन पहुँच रहे हैं।

विज्ञापन सहायक होते हैं?

  1. ((a))

    नौकरी दिलाने में

  2. ((b))

    उत्पाद को उपयुक्त उपभोक्ता तक पहुँचाने में

  3. ((c))

    प्रतियोगी परीक्षा में सफल होने में

  4. ((d))

    एजेंसियों का विस्तार सीमित करने में

Show Answer
Answer: ((b))

उत्पाद को उपयुक्त उपभोक्ता तक पहुँचाने में

सही उत्तर है- उत्पाद को उपयुक्त उपभोक्ता तक पहुँचाने में

Key Pointsगद्यांश के अनुसार-

  • “विज्ञापन से उत्पाद को उसके उपयुक्त उपभोक्ता तक पहुँचाने में सहायता मिलती है।”
13

निम्नलिखित गद्यांश को ध्यानपूर्वक पढ़कर उसपर आधारित प्रश्न का सही उत्तर दीजिए :

               वर्तमान समय में विज्ञापन का विशेष महत्व है। उपभोक्ता वर्ग के एक बहुत बड़े वर्ग में किसी उत्पाद को खरीदने से पहले विज्ञापन द्वारा उसके बारे में जानकारी प्राप्त करने की प्रवृत्ति रही है। विज्ञापन से उत्पाद को उसके उपयुक्त उपभोक्ता तक पहुँचाने में सहायता मिलती है। भारत ही नहीं संपूर्ण विश्व में विज्ञापन एजेंसियों का बहुत बड़ा तंत्र सक्रिय है। विज्ञापन एजेंसियों के कार्यालय अधिकतर महानगरों में हैं। दूर दराज के क्षेत्रों में भी रेडियो, टेलीविज़न और समाचार पत्रों के माध्यम से विज्ञापन पहुँच रहे हैं।

विज्ञापन एजेंसियों का तंत्र कहाँ तक फैला है?

  1. ((a))

    शहर

  2. ((b))

    महानगर

  3. ((c))

    राजधानियों

  4. ((d))

    संपूर्ण विश्व

Show Answer
Answer: ((d))

संपूर्ण विश्व

सही उत्तर है- संपूर्ण विश्व

Key Pointsगद्यांश के अनुसार-

  • भारत ही नहीं संपूर्ण विश्व में विज्ञापन एजेंसियों का बहुत बड़ा तंत्र सक्रिय है।
  • यह वाक्य स्पष्ट रूप से बता रहा है कि विज्ञापन एजेंसियों का तंत्र पूरे विश्व तक फैला हुआ है।
14

निम्नलिखित गद्यांश को ध्यानपूर्वक पढ़कर उसपर आधारित प्रश्न का सही उत्तर दीजिए :

              वर्तमान समय में विज्ञापन का विशेष महत्व है। उपभोक्ता वर्ग के एक बहुत बड़े वर्ग में किसी उत्पाद को खरीदने से पहले विज्ञापन द्वारा उसके बारे में जानकारी प्राप्त करने की प्रवृत्ति रही है। विज्ञापन से उत्पाद को उसके उपयुक्त उपभोक्ता तक पहुँचाने में सहायता मिलती है। भारत ही नहीं संपूर्ण विश्व में विज्ञापन एजेंसियों का बहुत बड़ा तंत्र सक्रिय है। विज्ञापन एजेंसियों के कार्यालय अधिकतर महानगरों में हैं। दूर दराज के क्षेत्रों में भी रेडियो, टेलीविज़न और समाचार-पत्रों के माध्यम से विज्ञापन पहुँच रहे हैं।

दूरदराज के क्षेत्रों में विज्ञापन पहुँचाने में निम्नलिखित में से कौन सा सहायक नहीं है?

  1. ((a))

    इंटरनेट

  2. ((b))

    रेडियो

  3. ((c))

    टेलीविज़न

  4. ((d))

    समाचार पत्र

Show Answer
Answer: ((a))

इंटरनेट

सही उत्तर है- इंटरनेट

Key Pointsगद्यांश के अनुसार-

  • दूर दराज के क्षेत्रों में भी रेडियो, टेलीविज़न और समाचार-पत्रों के माध्यम से विज्ञापन पहुँच रहे हैं।
  • गद्यांश में केवल तीन माध्यमों का उल्लेख है:
  • रेडियो
  • टेलीविज़न
  • समाचार-पत्र
15

निम्नलिखित गद्यांश को ध्यानपूर्वक पढ़कर उसपर आधारित प्रश्न का सही उत्तर दीजिए :

वर्तमान समय में विज्ञापन का विशेष महत्व है। उपभोक्ता वर्ग के एक बहुत बड़े वर्ग में किसी उत्पाद को खरीदने से पहले विज्ञापन द्वारा उसके बारे में जानकारी प्राप्त करने की प्रवृत्ति रही है। विज्ञापन से उत्पाद को उसके उपयुक्त उपभोक्ता तक पहुँचाने में सहायता मिलती है। भारत ही नहीं संपूर्ण विश्व में विज्ञापन एजेंसियों का बहुत बड़ा तंत्र सक्रिय है। विज्ञापन एजेंसियों के कार्यालय अधिकतर महानगरों में हैं। दूर दराज के क्षेत्रों में भी रेडियो, टेलीविजन और समाचार-पत्रों के माध्यम से विज्ञापन पहुँच रहे हैं।

निम्नलिखित में असंगत युग्म है :

  1. ((a))

    उपयुक्त - अनुपयुक्त

  2. ((b))

    सक्रिय - निष्क्रिय

  3. ((c))

    अधिकतर - कमतर

  4. ((d))

    पूर्ण - संपूर्ण

Show Answer
Answer: ((c))

अधिकतर - कमतर

सही उत्तर है- अधिकतर - कमतर

Key Points

युग्मक्या ये विलोम हैं?कारण
1) उपयुक्त - अनुपयुक्त✓ सही विलोमउपयुक्त = suitable, अनुपयुक्त = unsuitable
2) सक्रिय - निष्क्रिय✓ सही विलोमसक्रिय = active, निष्क्रिय = inactive
3) अधिकतर - कमतरअसंगत“अधिकतर” का विलोम “अल्पतर” या “कम” होता है। “कमतर” का अर्थ ही “हीन, निम्न स्तर का” होता है, मात्रा का नहीं। इसलिए यह विलोम नहीं है।
4) पूर्ण - संपूर्ण✓ सही पर्यायदोनों शब्द पर्यायवाची हैं, विलोम नहीं, लेकिन प्रश्न में “असंगत युग्म” पूछा है। विलोम के संदर्भ में यह भी संगत है क्योंकि ये एक-दूसरे के विलोम नहीं हैं, पर विकल्प 3 स्पष्ट रूप से गलत है।
16

निम्नलिखित में असंगत युग्म है :

  1. ((a))

    वर्ष में एक बार प्रकाशित होने वाला - वार्षिक

  2. ((b))

    सप्ताह में एक बार प्रकाशित होने वाला - साप्ताहिक

  3. ((c))

    पंद्रह दिन में एक बार प्रकाशित होने वाला - पाक्षिक

  4. ((d))

    माह में एक बार प्रकाशित होने वाला - माहिक

Show Answer
Answer: ((d))

माह में एक बार प्रकाशित होने वाला - माहिक

सही उत्तर है - माह में एक बार प्रकाशित होने वाला - माहिक

Key Points

  • माह में एक बार प्रकाशित होने वाला - मासिक

 

आवृत्तिसही शब्दअर्थ
वर्ष में एक बारवार्षिकAnnual
माह में एक बारमासिकMonthly
सप्ताह में एक बारसाप्ताहिकWeekly
पंद्रह दिन में एक बारपाक्षिकFortnightly (15 दिन या हर पखवाड़े में)
हर छह माह में एक बारअर्धवार्षिकHalf-yearly
हर तीन माह में एक बारत्रैमासिकQuarterly
17

निम्नलिखित में तत्सम शब्द नहीं है :

  1. ((a))

    अग्नि

  2. ((b))

    स्वामी

  3. ((c))

    पाँख

  4. ((d))

    वायु

Show Answer
Answer: ((c))

पाँख

सही उत्तर- पाँख

Key Points

शब्दप्रकारकारण
अग्नितत्समसंस्कृत से ज्यों-का-त्यों (अग्नि)
स्वामीतत्समसंस्कृत से ज्यों-का-त्यों (स्वामी)
पाँखतद्भवसंस्कृत “पक्ष” → प्राकृत → हिंदी में “पाँख” बना। यह विकृत रूप है, इसलिए तद्भव
वायुतत्समसंस्कृत से ज्यों-का-त्यों (वायु)

 

Additional Information

  • निष्कर्ष: “पाँख” तद्भव शब्द है, शेष तीनों तत्सम हैं।'पाँख' (या पंख) शब्द का तत्सम रूप 'पक्ष' होता है
18

'अश्व' शब्द का पर्यायवाची शब्द है :

  1. ((a))

    हय

  2. ((b))

    षट्पद

  3. ((c))

    हंस

  4. ((d))

     भृंग

Show Answer
Answer: ((a))

हय

'अश्व' का पर्यायवाची शब्द है- हय

Key Points

  • 'अश्व' के अन्य पर्यायवाची शब्द - घोड़ा, घोटक, हरि, हय, वाजि, सैन्धव, रविपुत्र।
  • पर्यायवाची - ऐसे शब्द जिनके अर्थ समान हों, पर्यायवाची शब्द कहलाते हैं।

Additional Information कुछ महत्वपूर्ण पर्यायवाची शब्द -

शब्दपर्यायवाची शब्द
घरगृह, सदन, आवास, आलय, गेह, निवास, निलय, मंदिर।
​कमलजलज, पंकज, सरोज, राजीव, अरविन्द, नीरज।
​पुत्रबेटा, सुत, तनय, आत्मज, जनज, लड़का, तनुज।
​स्त्रीललना, नारी, कामिनी, रमणी, महिला, वनिता, कांता।
​चोरतस्कर, दस्यु, रजनीचर, मोषक, कुंभिल, खनक।
वृक्षतरु, द्रुम, पादप, विटप, अगम, पेड़, गाछ।
​किरणमरीचि, मयूख, अंशु, कर, रश्मि, प्रभा, अर्चि, गो।
सिंहशेर, वनराज, शार्दूल, मृगराज, व्याघ्र, मृगेंद्र, महावीर।
19

प्रयोग के अनुसार सर्वनाम के भेद है :

  1. ((a))

    तीन

  2. ((b))

    चार

  3. ((c))

    पाँच

  4. ((d))

    छ:

Show Answer
Answer: ((d))

छ:

प्रयोग के अनुसार सर्वनाम के भेद है-  

Important Points

संज्ञा के स्थान पर प्रयुक्त होने वाले शब्दों को सर्वनाम कहते हैं। जैसे - मैं, वह, वे, उन्हें, अपने तुम, हम आदि। हिंदी में सर्वनामों की संख्या 11 है – ‘मैं, तू, आप, यह, वह, जो, सो, कोई, कुछ, कौन, क्या’ सर्वनाम के छः भेद हैं -
निश्चयवाचक सर्वनामजो सर्वनाम शब्द किसी व्यक्ति, वस्तु आदि का निश्चयपूर्वक बोध कराते हैं वे निश्चयवाचक सर्वनाम कहलाते हैं। जैसे - वे, यह, वह आदि।
पुरुषवाचक (व्यक्तिवाचक) सर्वनामजिस सर्वनाम का प्रयोग वक्ता द्वारा स्वयं के लिए या अन्य व्यक्ति के लिए किया जाता है। जैसे - मैं, हम, मुझे, तू, तुम, तुझे, तुम्हारा, वह, वे, उसने आदि।
निजवाचक सर्वनामजहाँ स्वयं के लिए 'आप, अपना, अपने आप' शब्दों का प्रयोग हो। जैसे - वह अपने आप ही घर चली गयी।
प्रश्नवाचक सर्वनामजो सर्वनाम शब्द संज्ञा के स्थान पर आकर वाक्य को प्रश्वाचक बनाते हैं। जैसे - क्या, कौन आदि।
अनिश्चयवाचक सर्वनामजिन सर्वनाम शब्दों से वस्तु, व्यक्ति, स्थान आदि की निश्चितता का बोध नही होता वे अनिश्चयवाचक सर्वनाम कहलाते हैं। जैसे- कुछ, कोई आदि।
सम्बन्धवाचक सर्वनामजिन सर्वनाम शब्दों का प्रयोग किसी वस्तु या व्यक्ति का सम्बन्ध बताने के लिए किया जाए वे शब्द सम्बन्धवाचक सर्वनाम कहलाते हैं। जैसे - जो-सो, जैसा-वैसा आदि।
20

'मनोभाव' का सन्धिविच्छेद है :

  1. ((a))

    मनो + भाव

  2. ((b))

    मनः + भाव

  3. ((c))

    मन + उभाव

  4. ((d))

    मनोभ + आव

Show Answer
Answer: ((b))

मनः + भाव

'मनोभाव' में : विसर्ग संधि है।

  • संधि विच्छेद: मनः+भाव
  • विसर्ग संधि के उदाहरण
  • तपः + बल = तपोबल
  • पुरः + हित = पुरोहित

Key Points 

  • विसर्ग संधि के प्रकार
  • सत्व विसर्ग संधि
  • उत्व संधि
  • रूत्व संधि

Additional Information

1. सत्व विसर्ग संधि

  • यदि किसी भी पद के आखिर में या अंत में “अ” स्वर के अलावा कोई अन्य स्वर आये और उसके बाद में विसर्ग आये तथा दूसरे शब्द के शुरू में वर्ण का तीसरा, चौथा, पांचवा अक्षर “य्, र्, ल्, व्” में से कोई आये तो वर्ण अगले वर्ण के ऊपर चढ़ जाता है और विसर्ग “र” हो जाता है।

जैसे:

  • बहि: + अंग = बहिरंग
  • आशि: + वाद = आशिर्वाद

 

2. उत्व संधि

  • यदि किसी प्रथम पद के आखिर या अन्त मे “अ” आये उसके बाद मे विसर्ग आये तथा दूसरे पद के शुरुआत् क तीसरा, चौथा, पांचवा “य्, र्, ल्, व्” में से कोई आये तो “उ” बन जाता है,
  • अतः अ+उ = ओ हो जाता है।

जैसे :

  • तप + वन = तपोवन
  • मन + हर = मनोहर
  1. रूत्व संधि
  • यदि किसी पद के अन्त मे कोई भी स्वर आने के पश्चात विसर्ग आये तथा उसके बाद दूसरे पद के शुरुआत् मे “त/थ” आने पर “स” बन जाता है।
  • यदि “च/छ्” आता है तो “श” बन जाता है, उसके बाद मे “ट/ठ” आने पर “ष” बन जाता है।

जैसे :

  • चन्द्र: + तम् = चन्द्र्स्तम्
  • नि: + चय = निश्चय
  • धनु: + टकार = धनुष्टकार

GK, LR & Computer (20 questions)

21

Assertion (A): State can impose reasonable restriction on the exercise of right to freedom of speech and expression guaranteed by the Indian constitution.

Reasonable restriction cannot be imposed on right to freedom of speech and expression in relation to contempt of court. Reason (R):

Choose the correct answer from the codes below:

  1. ((a))

    (A) is correct but (R) is wrong

  2. ((b))

    Both (A) and (R) are correct and (R) explains (A)

  3. ((c))

    Both (A) and (R) are correct but (R) does not explain (A)

  4. ((d))

    Both (A) and (R) are wrong

Show Answer
Answer: ((a))

(A) is correct but (R) is wrong

The correct answer is 1.

Key Points

  • Article 19(1)(a) of the Indian Constitution guarantees the fundamental right to freedom of speech and expression to all citizens.
  • However, reasonable restrictions can be imposed by the State on this right under Article 19(2) of the Constitution.
  • These restrictions are imposed in the interest of sovereignty and integrity of India, security of the State, friendly relations with foreign States, public order, decency, morality, contempt of court, defamation, incitement to an offense, or reasonable restrictions as prescribed by law.
  • The assertion that the State can impose reasonable restrictions on the right to freedom of speech and expression is correct. This ensures that the right is balanced with societal order and national security.
  • The reason stating that reasonable restrictions cannot be imposed in relation to contempt of court is incorrect, as contempt of court is explicitly mentioned under Article 19(2) as a valid ground for restriction.

Additional Information

  • Article 19(1)(a):
  • This article provides the fundamental right to freedom of speech and expression, allowing citizens to freely express their views, opinions, and ideas.
  • This right is essential for the functioning of a democratic society and includes rights such as freedom of the press.
  • Reasonable Restrictions under Article 19(2):
  • Article 19(2) empowers the State to impose restrictions on the freedom of speech and expression under specific conditions such as public order, decency, morality, contempt of court, defamation, or incitement to an offense.
  • These restrictions must be reasonable and justified in a court of law.
  • Contempt of Court:
  • Contempt of Court is a legal provision aimed at protecting the authority and dignity of courts in India.
  • Under the Contempt of Courts Act, 1971, contempt is classified into civil contempt (disobedience of court orders) and criminal contempt (actions that scandalize or lower the authority of the court).
  • Reasonable restrictions on freedom of speech in relation to contempt of court ensure that judicial processes are not obstructed.
  • Defamation:
  • Defamation refers to a false statement made by one individual about another, which causes harm to the reputation of the latter.
  • Reasonable restrictions on speech prevent misuse of the right to harm others' reputations unjustly.
  • Public Order and Morality:
  • Restrictions on speech and expression can be imposed to maintain public order and uphold moral standards within the society.
  • For example, hate speeches inciting violence or content violating societal norms can be restricted under these grounds.

Important Points

  • Freedom of Speech in India:
  • Freedom of speech and expression is not absolute; it is subject to reasonable restrictions to ensure harmony and order within society.
  • Judicial interpretation plays a critical role in balancing individual rights with societal needs.
  • Judicial Precedents:
  • Landmark cases such as Keshavananda Bharati v. State of Kerala and Maneka Gandhi v. Union of India have shaped the understanding of reasonable restrictions on fundamental rights.
  • Courts ensure that restrictions are not arbitrary and follow principles of natural justice.
  • Global Perspective:
  • Freedom of speech is recognized internationally under instruments like Article 19 of the Universal Declaration of Human Rights (UDHR).
  • However, similar restrictions exist in other democracies to prevent misuse of the right.
22

Which of the following statements is correct about the 'Agile' approach to policy making?

  1. ((a))

    It follows a rigid up-front plan for implementation

  2. ((b))

    It does not use feedback loops

  3. ((c))

    It uses real-time adjustment

  4. ((d))

    It is the same as the 'waterfall' framework to policy making

Show Answer
Answer: ((c))

It uses real-time adjustment

The correct answer is It uses real-time adjustment.

Key Points

  • Agile approach to policy-making is characterized by its ability to adapt and adjust policies in real-time based on feedback, data, and changing circumstances. Hence, statement 3 is correct.
  • The Agile approach does not follow a rigid up-front plan for implementation. Instead, it emphasizes flexibility and iterative development. Hence, statement 1 is incorrect.
  • This approach actively utilizes feedback loops to refine and improve policies during the implementation process. Hence, statement 2 is incorrect.
  • The Agile approach is distinct from the 'Waterfall' framework, which follows a linear and sequential process. Agile is more dynamic and iterative. Hence, statement 4 is incorrect.
  • Agile policy-making is particularly useful in complex and uncertain environments, where the ability to respond quickly to new challenges is crucial.

Additional Information

  • Key Features of Agile Policy-Making:
  • Iterative Process: Policies are developed and implemented in small, manageable phases, allowing for frequent reassessment and adjustment.
  • Stakeholder Engagement: Continuous involvement of stakeholders ensures that the policies remain relevant and practical.
  • Data-Driven Decisions: Real-time data and analytics are used to inform and guide policy changes.
  • Flexibility: Agile policy-making allows for quick adjustments in response to unforeseen challenges or changing circumstances.
  • Waterfall Framework:
  • The Waterfall approach is linear and sequential, with clearly defined stages such as planning, design, implementation, and evaluation.
  • It is best suited for projects with well-defined goals and stable environments.
  • Unlike Agile, it does not allow for changes once a stage has been completed.
  • Applications of Agile Policy-Making:
  • It is widely used in technology and software development, where rapid changes are the norm.
  • Governments and organizations use Agile methods to address public health crises, such as the COVID-19 pandemic, by adapting policies in real-time.
  • It is also applied in climate change policies, where dynamic adjustments are required based on emerging data.
  • Benefits of Agile Policy-Making:
  • Enhanced Responsiveness: Ability to quickly address new challenges and opportunities.
  • Improved Outcomes: Continuous improvement leads to more effective and impactful policies.
  • Stakeholder Satisfaction: Regular feedback ensures that policies meet the needs of the people they are designed for.

Important Points

  • The Agile approach is increasingly being adopted in public administration to address complex societal challenges.
  • Examples of Agile policy-making include adaptive climate policies and public health strategies during the pandemic.
  • It contrasts with traditional approaches by emphasizing flexibility, collaboration, and data-driven decision-making.
23

Who had devised the policy called the 'Doctrine of Lapse' in Colonial India ?

  1. ((a))

    Lord Dalhousie

  2. ((b))

    Lord Hastings

  3. ((c))

    Lord Cornwallis

  4. ((d))

    Lord Wellesley

Show Answer
Answer: ((a))

Lord Dalhousie

The correct answer is Lord Dalhousie.

Key Points

  • Lord Dalhousie, who served as the Governor-General of India from 1848 to 1856, was the architect of the Doctrine of Lapse.
  • The Doctrine of Lapse was a policy of annexation used by the British East India Company to expand its territorial control in India.
  • Under this doctrine, if an Indian ruler died without a legitimate male heir, the state would "lapse" and be annexed by the British. The term "legitimate male heir" excluded adopted sons, which was a common Indian practice for succession.
  • Several princely states were annexed using this policy, including Satara (1848), Sambalpur (1850), Jhansi (1853), and Awadh (1856).
  • The Doctrine of Lapse became one of the major causes of resentment among Indian rulers and contributed to the outbreak of the Revolt of 1857.

Additional Information

  • Lord Dalhousie:
  • Lord Dalhousie is remembered as one of the most significant British administrators in India, known for his expansionist policies and reforms.
  • Besides the Doctrine of Lapse, Dalhousie is credited with introducing modern infrastructure like railways, telegraphs, and postal services in India.
  • He also implemented reforms in education, introducing the Wood's Despatch of 1854, which laid the foundation for the modern education system in India.
  • Doctrine of Lapse:
  • The doctrine was introduced to consolidate British authority in India by annexing states that failed to produce a male heir.
  • The policy disregarded Indian traditions, especially the practice of adoption, leading to widespread resentment among Indian rulers.
  • The annexation of Jhansi under this doctrine deeply angered its queen, Rani Lakshmi Bai, who became one of the leading figures in the Revolt of 1857.
  • Impact of the Doctrine:
  • The aggressive annexation of Indian states alienated the Indian rulers and nobility, creating widespread discontent against British rule.
  • The annexation of Awadh (1856) under the pretext of misgovernance, further compounded grievances among the Indian population, especially soldiers who hailed from Awadh.
  • This resentment played a crucial role in the Revolt of 1857, often referred to as the First War of Indian Independence.
  • Other Governors-General and Their Contributions:
  • Lord Hastings: Known for his role in the Anglo-Nepalese War (1814–1816) and the creation of the Ryotwari system of land revenue.
  • Lord Cornwallis: Introduced the Permanent Settlement (1793), which fixed land revenue and created the zamindari system.
  • Lord Wellesley: Known for his use of the Subsidiary Alliance system, which helped the British control Indian princely states indirectly.
24

Which of the following is the finest iron ore with high content of iron upto 70%?

  1. ((a))

    Hematite

  2. ((b))

    Magnetite

  3. ((c))

    Mica

  4. ((d))

    Cobalt

Show Answer
Answer: ((b))

Magnetite

The correct answer is Magnetite.

Key Points

  • Magnetite is the finest quality iron ore with the highest iron content, up to 70%. It is considered the most valuable among all types of iron ores.
  • It is composed of iron oxide (Fe₃O₄), which has both ferrous (Fe²⁺) and ferric (Fe³⁺) ions, contributing to its high iron content.
  • Magnetite is known for its magnetic properties, which differentiate it from other iron ores like Hematite. These properties make it useful in various industrial processes.
  • It is found in regions like India, Australia, Brazil, and the USA. In India, magnetite is primarily located in the states of Karnataka, Andhra Pradesh, and Goa.
  • Due to its high iron content and purity, magnetite is extensively used in the steel industry for the production of high-quality steel.

Additional Information

  • Hematite:
  • Hematite is another important iron ore and contains around 50-60% iron.
  • It is composed of iron(III) oxide (Fe₂O₃) and is known for its reddish-brown color.
  • Hematite is widely distributed and is a major source of iron for industries.
  • It is primarily found in states like Odisha, Jharkhand, and Chhattisgarh in India.
  • Mica:
  • Mica is a non-metallic mineral known for its insulating and heat-resistant properties.
  • It is widely used in the electrical and electronics industries.
  • Mica is found in states like Jharkhand, Rajasthan, and Andhra Pradesh in India.
  • Cobalt:
  • Cobalt is a metallic element primarily used in the production of rechargeable batteries, alloys, and catalysts.
  • It is not an iron ore and is typically obtained as a by-product of nickel and copper mining.
  • Globally, major cobalt-producing countries include the Democratic Republic of Congo, Russia, and Canada.
  • Iron Ore in India:
  • India has large reserves of iron ore, primarily found in states like Odisha, Karnataka, Chhattisgarh, and Jharkhand.
  • Iron ore is a critical raw material for the steel industry, which forms the backbone of industrial development in the country.
  • Important Points:
  • Magnetite has the highest iron content, making it the finest quality iron ore.
  • Hematite, though slightly lower in iron content, is more abundant and widely used.
  • Mica and cobalt are not forms of iron ore and serve different industrial purposes.
25

Which among the following was the earliest arms control treaty which banned nuclear weapon tests in the outer space and under water?

  1. ((a))

    Nuclear Non-Proliferation Treaty

  2. ((b))

    Limited Test Ban Treaty

  3. ((c))

    Strategic Arms Limitation Talks I

  4. ((d))

    Comprehensive Nuclear Test Ban Treaty

Show Answer
Answer: ((b))

Limited Test Ban Treaty

The correct answer is Limited Test Ban Treaty.

Key Points

  • The Limited Test Ban Treaty (LTBT), also known as the Partial Test Ban Treaty, was signed on 5 August 1963, and came into effect on 10 October 1963.
  • The LTBT was the earliest arms control treaty aimed at banning nuclear weapon tests in the atmosphere, outer space, and underwater. It was a significant step toward reducing environmental contamination caused by nuclear testing.
  • It was signed between the United States, the Soviet Union, and the United Kingdom, with later accession by other nations.
  • The treaty did not ban underground nuclear tests, which were later addressed by other agreements.
  • The LTBT was a landmark agreement during the Cold War era, showing international cooperation in reducing the dangers associated with nuclear weapons testing.

Additional Information

  • Nuclear Non-Proliferation Treaty (NPT):
  • The NPT was opened for signature on 1 July 1968 and came into force on 5 March 1970.
  • It aims to prevent the spread of nuclear weapons, promote peaceful uses of nuclear energy, and achieve nuclear disarmament.
  • The treaty has three pillars: non-proliferation, disarmament, and the right to peacefully use nuclear technology.
  • While it is a crucial treaty in nuclear arms control, it does not specifically address nuclear testing bans.
  • Strategic Arms Limitation Talks I (SALT I):
  • SALT I was a series of negotiations between the United States and the Soviet Union in the early 1970s to limit the arms race.
  • It resulted in the Anti-Ballistic Missile Treaty (ABM Treaty) and an interim agreement on the limitation of strategic offensive arms.
  • These agreements were signed in 1972, but SALT I did not address nuclear testing.
  • Comprehensive Nuclear Test Ban Treaty (CTBT):
  • The CTBT was adopted by the United Nations General Assembly on 10 September 1996.
  • It bans all nuclear explosions for both civilian and military purposes in all environments.
  • As of October 2023, the treaty has not entered into force because some key states, including the United States and China, have not ratified it.
  • Environmental and Political Impact of LTBT:
  • The LTBT significantly reduced the fallout from atmospheric nuclear tests, which were causing widespread environmental and health issues.
  • It was an important confidence-building measure during the Cold War, leading to further negotiations on arms control and disarmament.

Important Points

  • Scope of LTBT:
  • The treaty prohibited nuclear tests in the atmosphere, outer space, and underwater, but allowed underground tests.
  • It was an important precursor to the Comprehensive Nuclear Test Ban Treaty (CTBT).
  • Signatory Nations:
  • The LTBT initially involved the United States, Soviet Union, and the United Kingdom. Other nations joined later, reflecting growing international support for arms control.
  • Legacy of the LTBT:
  • The treaty laid the foundation for future arms control agreements, including the CTBT and other disarmament initiatives.
  • It demonstrated the possibility of cooperation between rival powers to address global security challenges.
26

Which of the following units makes Cellulose ?

  1. ((a))

    Fructose

  2. ((b))

    Glucose

  3. ((c))

    Sucrose

  4. ((d))

    Ribose

Show Answer
Answer: ((b))

Glucose

The correct answer is Glucose.

Key Points

  • Cellulose is a complex carbohydrate or polysaccharide made up of repeating units of glucose.
  • The glucose units are linked together by β-1,4 glycosidic bonds, which form linear chains.
  • Cellulose is the primary structural component of the cell walls in plants, providing rigidity and strength.
  • Unlike starch, cellulose is not digestible by humans because we lack the enzyme cellulase required to break β-1,4 bonds.
  • Cellulose is synthesized in plants from glucose molecules during photosynthesis, which is subsequently polymerized to form cellulose chains.

Additional Information

  • Fructose:
  • Fructose is a simple sugar (monosaccharide) found naturally in fruits, honey, and vegetables.
  • It is not involved in the synthesis of cellulose.
  • Fructose is used by the body for energy production but does not polymerize to form structural carbohydrates like cellulose.
  • Sucrose:
  • Sucrose is a disaccharide made of one molecule of glucose and one molecule of fructose.
  • It is commonly known as table sugar and serves as an energy source rather than a structural component.
  • Sucrose is not a building block for cellulose synthesis.
  • Ribose:
  • Ribose is a monosaccharide essential for the formation of nucleotides and nucleic acids like RNA and DNA.
  • It is a five-carbon sugar and does not contribute to cellulose formation.
  • Ribose is primarily used in genetic material synthesis rather than carbohydrate polymers like cellulose.
  • Importance of Cellulose:
  • Cellulose is the most abundant organic polymer on Earth.
  • It is utilized in various industries for the production of paper, textiles, and biofuels.
  • Its biodegradability makes it an environmentally sustainable material.

Important Points

  • Humans cannot digest cellulose due to the absence of cellulase, but it serves as dietary fiber, aiding digestion.
  • Ruminants like cows and goats can digest cellulose with the help of symbiotic bacteria in their stomachs.
  • Cellulose has applications in the production of biodegradable plastics and pharmaceuticals.
27

Which of the following are Oviparous animals ?

  1. ((a))

    Hen and Cat

  2. ((b))

    Cat and Dog

  3. ((c))

    Crow and Dog

  4. ((d))

    Hen and Crow

Show Answer
Answer: ((d))

Hen and Crow

The correct answer is Hen and Crow.

Key Points

  • Oviparous animals are those that lay eggs, with the embryo developing and hatching outside the mother’s body. Examples include birds, reptiles, amphibians, and most fish.
  • Hen is a bird and an oviparous animal that lays eggs. The eggs are incubated to hatch into chicks. Hence, it is correctly classified as oviparous.
  • Crow, like all birds, is an oviparous animal. It lays eggs, and the chicks hatch after a specific incubation period. Hence, it is also correctly classified as oviparous.
  • Cat and Dog are mammals and are classified as viviparous animals. They give birth to live young ones, not eggs. Thus, they are not oviparous.
  • Option 4 (Hen and Crow) is correct as both are oviparous animals. Options containing Cat and Dog, such as Option 1, Option 2, and Option 3, are incorrect.

Additional Information

  • Characteristics of Oviparous Animals:
  • Oviparous animals lay eggs, and fertilization can either be external (e.g., fish and amphibians) or internal (e.g., birds and reptiles).
  • The eggs are protected by shells or membranes and contain nutrients for the developing embryo.
  • Examples include birds like hens, reptiles like turtles, amphibians like frogs, and insects like butterflies.
  • Viviparous Animals:
  • These animals give birth to live young ones, with the embryo developing inside the mother's body.
  • Nourishment is provided directly to the embryo through specialized structures like the placenta in mammals.
  • Examples include mammals like cats, dogs, humans, and whales.
  • Incubation in Birds:
  • Birds like hens and crows incubate their eggs by sitting on them to provide warmth.
  • The incubation period varies by species; for instance, a hen's egg typically hatches in about 21 days.
  • Adaptations in Oviparous Animals:
  • Eggs of oviparous animals have adaptations like hard shells (birds) or jelly-like coverings (amphibians) to protect against environmental factors and predators.
  • Some oviparous animals exhibit parental care, such as guarding the eggs or constructing nests.
  • Important Facts:
  • Among vertebrates, mammals are predominantly viviparous, while most other classes like birds, reptiles, fish, and amphibians are oviparous.
  • Insects, another major group of oviparous animals, often lay large numbers of eggs to increase the chances of survival.
28

Who among the following players won the FIFA World Cup 2022, 'Young Player of the Tournament' award? 

  1. ((a))

    Kylian Mbappe

  2. ((b))

    Alexis Mac Allister

  3. ((c))

    Rodrigo De Paul

  4. ((d))

    Enzo Fernandez

Show Answer
Answer: ((d))

Enzo Fernandez

The correct answer is Enzo Fernandez.

Key Points

  • Enzo Fernandez was awarded the 'Young Player of the Tournament' at the FIFA World Cup 2022, held in Qatar.
  • This award is given to the best-performing young player (under 21 years of age) in the tournament. Enzo Fernandez played a pivotal role in Argentina's success during the World Cup.
  • He contributed significantly to Argentina's midfield with his dynamic gameplay, creativity, and defensive contributions. His standout performances included a crucial goal against Mexico in the group stage.
  • Enzo Fernandez was only 21 years old during the tournament and was representing Argentina. He plays as a midfielder and showcased exceptional technical and tactical skills.
  • His recognition as the 'Young Player of the Tournament' highlights his potential and marks him as one of the rising stars in international football.

Additional Information

  • About Enzo Fernandez:
  • Full Name: Enzo Jeremías Fernández.
  • Date of Birth: 17 January 2001. He was born in San Martín, Argentina.
  • He started his professional football career with River Plate in Argentina before moving to SL Benfica in Portugal.
  • Fernandez is known for his passing accuracy, game vision, and ability to control the tempo of the game.
  • FIFA 'Young Player of the Tournament' Award:
  • This award was introduced in the 2006 FIFA World Cup to recognize the best young talent in the tournament.
  • The recipient must be under the age of 21 at the beginning of the calendar year in which the World Cup is held.
  • Previous notable winners include Kylian Mbappe (2018) and Paul Pogba (2014).
  • FIFA World Cup 2022:
  • The tournament was held in Qatar from 20 November to 18 December 2022.
  • Argentina emerged as the champions, defeating France in a dramatic final that ended in a penalty shootout.
  • Lionel Messi was awarded the 'Golden Ball' for being the best player of the tournament, while Kylian Mbappe won the 'Golden Boot' for scoring the most goals (8).
  • Other Notable Performances:
  • Kylian Mbappe: Scored a hat-trick in the final and was the top scorer of the tournament.
  • Alexis Mac Allister: Played a crucial role in Argentina's midfield, complementing Enzo Fernandez.
  • Rodrigo De Paul: Provided defensive stability and leadership in Argentina’s midfield.
29

Who among the following authors won the 'Sahitya Akademi Yuva Puraskar 2022, in Sanskrit, language ? 

  1. ((a))

    Madhusudan Mishr

  2. ((b))

    Pankaj Kumar Jha

  3. ((c))

    Shruti Prasad Kanitkar

  4. ((d))

    Shubrajit Sen

Show Answer
Answer: ((a))

Madhusudan Mishr

The correct answer is Madhusudan Mishr.

Key Points

  • Madhusudan Mishr was awarded the prestigious 'Sahitya Akademi Yuva Puraskar 2022' for his contribution to the Sanskrit language.
  • The 'Sahitya Akademi Yuva Puraskar' is an annual award conferred by the Sahitya Akademi, India’s National Academy of Letters, to recognize young writers of exceptional talent in various Indian languages.
  • The award aims to honor and promote the literary works of individuals aged below 35 years in India.
  • Madhusudan Mishr’s work showcases the rich tradition of Sanskrit literature while incorporating modern themes, making it relevant to contemporary readers.
  • The award includes a cash prize of Rs. 50,000 along with a plaque, symbolizing recognition of literary excellence.

Additional Information

  • About Sahitya Akademi Yuva Puraskar:
  • The award was instituted in 2011 by the Sahitya Akademi.
  • It is presented in 24 Indian languages, including Sanskrit, Hindi, Tamil, Urdu, Bengali, and others.
  • It recognizes and encourages young authors whose works reflect the diversity of Indian culture and language.
  • Winners are selected based on the originality, creativity, and literary value of their work.
  • Madhusudan Mishr:
  • He is an emerging talent in the field of Sanskrit literature.
  • His award-winning work is a testament to his ability to blend traditional Sanskrit literary forms with contemporary issues and themes.
  • His contributions are significant in keeping the ancient language alive and relevant in modern times.
  • Sanskrit Language:
  • Sanskrit is one of the oldest languages in the world and is often referred to as the mother of many Indian languages.
  • It is recognized as a classical language by the Government of India.
  • Sanskrit has a rich literary tradition, including works like the Vedas, Upanishads, Mahabharata, Ramayana, and Puranas.
  • Efforts are being made to revive and promote Sanskrit through various government initiatives, educational programs, and literary awards.
  • Other Authors Nominated in 2022 (in Sanskrit):
  • While other authors such as Pankaj Kumar Jha and Shruti Prasad Kanitkar have notable works, the award for Sanskrit language in 2022 was solely conferred upon Madhusudan Mishr.
30

Match the terms given in List - I with their nature/use in List - II.

List - IList - II
(A) USB(I) Enables user to access programs on a computer through image objects that are linked to the programs
(B) GUI(II) A file format used for compressed image files
(C) GIF(III) A software designed to take a scanned text as input and convert it into its ASCII coded equivalent
(D) OCR(IV) Connects peripherals in which data is transmitted serially

Select the correct answer using the codes given below:

  1. ((a))

    (A)-(1), (B)-(II), (C)-(III), (D)-(IV)

  2. ((b))

    (А)-(II), (B)-(III), (C)-(IV), (D)-(I)

  3. ((c))

    (A)-(III), (B)-(IV), (C)-(I), (D)-(II)

  4. ((d))

    (A)-(IV), (B)-(I), (C)-(II), (D)-(III)

Show Answer
Answer: ((d))

(A)-(IV), (B)-(I), (C)-(II), (D)-(III)

The correct answer is A - IV, B - I, C - II, D - III.

Key Points

  • USB (Universal Serial Bus):
  • USB is a standard protocol designed to connect peripheral devices (such as keyboards, mice, external drives) to a computer.
  • It enables serial data transmission, making it an efficient method for connecting and communicating with devices. Hence, the correct match for USB is IV.
  • GUI (Graphical User Interface):
  • GUI is a user interface that allows users to interact with electronic devices using graphical icons and visual indicators, rather than text-based interfaces or command-line prompts.
  • It simplifies user interaction with programs through linked image objects. Hence, the correct match for GUI is I.
  • GIF (Graphics Interchange Format):
  • GIF is a widely-used file format for compressed image files, enabling faster loading of images on websites.
  • It supports both static and animated images. Hence, the correct match for GIF is II.
  • OCR (Optical Character Recognition):
  • OCR is a technology that converts scanned text or images of text into machine-readable text formats (e.g., ASCII code).
  • It is extensively used for digitizing printed documents. Hence, the correct match for OCR is III.

Additional Information

  • USB (Universal Serial Bus):
  • USB was first introduced in 1996 and has since evolved into various versions, such as USB 2.0, USB 3.0, and USB-C.
  • It supports plug-and-play functionality, making device connections easier without requiring complex installation procedures.
  • USB is used in devices globally for charging and data transfer, and it supports numerous peripherals, including printers, cameras, and smartphones.
  • GUI (Graphical User Interface):
  • GUI was first developed by Xerox PARC in the 1970s and popularized by companies like Apple and Microsoft.
  • It is widely used in operating systems such as Windows, macOS, and Linux, enabling user-friendly navigation and functionality.
  • GUI-based systems have replaced traditional command-line interfaces in most consumer electronics.
  • GIF (Graphics Interchange Format):
  • GIF was introduced by CompuServe in 1987 and remains popular for sharing short, animated clips.
  • It uses lossless compression, ensuring that image quality is preserved while reducing file size.
  • GIFs are widely used on social media platforms and websites for visual communication.
  • OCR (Optical Character Recognition):
  • OCR technology emerged in the 1950s, with advancements enabling high-speed text recognition in modern applications.
  • It is used in various industries, including banking, document management, and legal services, to digitize and automate text processing.
  • Popular OCR software includes Adobe Acrobat, ABBYY FineReader, and Google Drive OCR.
31

Choose the correct alternative that will continue the same pattern and replace the question mark (?) in the given number series.

6, 24, 60, 120, 210, ?

  1. ((a))

    330

  2. ((b))

    336

  3. ((c))

    366

  4. ((d))

    396

Show Answer
Answer: ((b))

336

The logic followed here is:

Thus, the missing number in the series is "336".

Hence, the correct answer is "Option 2".

32

Nine books are kept one over the other. Counting from the bottom, the third and seventh books are Text Books. Two books of General Awareness are below a story book. One book on plays is above the Text Book and another book on plays is below the Text Book. One book on poetry is above the book on plays while the other book on poetry is below the book on plays. Which book is fifth from the bottom ? 

  1. ((a))

    Poetry Book

  2. ((b))

    Plays Book

  3. ((c))

    Story Book

  4. ((d))

    General Awareness Book

Show Answer
Answer: ((d))

General Awareness Book

Total number of books: 9. Positions are counted from the bottom (1) to the top (9).

  1. Counting from the bottom, the third and seventh books are Text Books.
  • Position 3: Text Book (TB)
  • Position 7: Text Book (TB)
Position (from Bottom)Book Type
9
8
7Text Book
6
5
4
3Text Book
2
1

 

  1. One book on plays is above the Text Book and another book on plays is below the Text Book.
Position (from Bottom)Book Type
Case I
Book Type
Case II
9Poetry Book
8Plays Book
7Text BookText Book
6Plays Book
5
4Plays Book
3Text BookText Book
2Plays Book
1Poetry Book
  1. One book on poetry is above the book on plays, and the other book on poetry is below the book on plays. 

Case II is not possible as one place is remaining and there are two poetry books.

Position (from Bottom)Book Type
Case I
9Poetry Book
8Plays Book
7Text Book
6
5
4
3Text Book
2Plays Book
1Poetry Book

 

  1. Two books of General Awareness are below a story book.
Position (from Bottom)Book Type
Case I
9Poetry Book
8Plays Book
7Text Book
6Story Book
5General Awareness Book
4General Awareness Book
3Text Book
2Plays Book
1Poetry Book

 

The book at the fifth from the bottom is the "General Awareness Book".

Hence, the correct answer is "Option 4".

33

If 'North-East' is called 'West', 'South-East is called 'North', 'South-West' is called 'East' and 'North-West' is called 'South'. What will 'Easť be called ? 

  1. ((a))

    North-West

  2. ((b))

    North-East

  3. ((c))

    South-West

  4. ((d))

    South-East

Show Answer
Answer: ((a))

North-West

Given that: 'North-East' is called 'West', 'South-East is called 'North', 'South-West' is called 'East', and 'North-West' is called 'South'.

The conventional direction diagram is given below:

Rotating the given diagram, 135º clockwise, in order to make South-East as North, we get the diagram as below:

From the figure, it is clear that East is called as North-West in the given system.

Hence, the correct answer is "Option 1".

34

A question is given below followed by two statements numbered I and II each containing some information. Decide which of the statements are sufficient to answer the question ?

Q. Rohan is in which direction with respect to Pankaj?

Statement I: Rohan is to the South of Tanya who is to the East of Dolly.

Statement II: Pankaj is to the East of Tanya.

  1. ((a))

    The statement I alone is sufficient to answer the question while the statement II alone is not sufficient to answer.

  2. ((b))

    The statement II alone is sufficient to answer the question while the statement I alone is not sufficient to answer.

  3. ((c))

    Both statements I and II together are necessary to answer the question.

  4. ((d))

    Both statements I and II together are not sufficient to answer.

Show Answer
Answer: ((c))

Both statements I and II together are necessary to answer the question.

Given:

Question: Rohan is in which direction with respect to Pankaj?

Statement I Analysis

I: Rohan is to the South of Tanya who is to the East of Dolly.

Conclusion: Statement I alone gives the relative positions of Rohan, Tanya, and Dolly. It does not mention Pankaj.

Therefore, Statement I alone is not sufficient.

Statement II Analysis

II: Pankaj is to the East of Tanya.

Conclusion: Statement II alone gives the relative position of Pankaj with respect to Tanya. It does not mention Rohan.

Therefore, Statement II alone is not sufficient.

Combining I and II:

The direction of Rohan from Pankaj is "South-West".

Both statements I and II together are necessary to answer the question.

Hence, the correct answer is "Option 3"

35

In the following figure, triangle represents men, circle represents post-graduates and square represents sub-inspectors of police.

 

Which number represents female post graduates, sub-inspectors of police ?

  1. ((a))

    5

  2. ((b))

    8

  3. ((c))

    9

  4. ((d))

    12

Show Answer
Answer: ((d))

12

The logic followed here is,

We are looking for the number that represents female post-graduates, sub-inspectors of police.

​The number must be in the region common to the circle and the square, but outside the triangle.

The figure represents the following categories:

Therefore, 12 represents female post-graduates who are sub-inspectors of police.

Hence, the correct answer is "Option 4".

36

The following is not by default installed with MS Windows. 

  1. ((a))

    MS Paint

  2. ((b))

    Notepad

  3. ((c))

    Clock

  4. ((d))

    MS PowerPoint

Show Answer
Answer: ((d))

MS PowerPoint

The correct answer is MS PowerPoint.

Key Points

  • MS Paint: This is a basic graphics editing application that is included by default in all MS Windows installations.
  • Notepad: Notepad is a simple text editor that comes pre-installed with Windows for editing plain text files.
  • Clock: The Clock application is also a default feature in Windows, providing a simple time and alarm management tool.
  • MS PowerPoint: MS PowerPoint is part of the Microsoft Office suite and is not included by default in the Windows operating system. It requires separate installation.

Additional Information

  • Microsoft Office Suite: Applications like MS Word, MS Excel, and MS PowerPoint are part of the Microsoft Office suite, which is a separate software package that needs to be purchased and installed on Windows.
  • Default Windows Applications: Applications like Calculator, Paint, Notepad, and Clock are pre-installed with Windows to provide basic functionalities to users.
37

_____________is not a basic function of MS Excel. 

  1. ((a))

    count()

  2. ((b))

    sum()

  3. ((c))

    max()

  4. ((d))

    addition()

Show Answer
Answer: ((d))

addition()

The correct answer is Option 4 (addition).

Key Points

  • MS Excel provides various built-in functions to perform calculations, analyze data, and manipulate values.
  • Functions like count(), sum(), and max() are standard and basic functions in MS Excel. They are used to count cells, calculate the sum of values, and find the maximum value, respectively.
  • However, "addition()" is NOT a function in MS Excel. Instead, Excel uses the sum() function to perform addition operations.
  • Thus, "addition()" is not a valid or basic function in MS Excel.

Additional Information

  • count(): Counts the number of cells containing numerical data in a range.
  • sum(): Adds up all the numerical values in a given range.
  • max(): Returns the largest value from a range of numbers.
  • addition(): Not a valid function in MS Excel; use the sum() function instead.
38

Which of the following is true about cell range in MS Excel? 

  1. ((a))

     Collection of chosen cells

  2. ((b))

     Collection of formula

  3. ((c))

     Collection of values

  4. ((d))

     Collection of occupied cells

Show Answer
Answer: ((a))

 Collection of chosen cells

The correct answer is Collection of chosen cells.

Key Points

  • In MS Excel, a cell range is a collection of selected or chosen cells.
  • A cell range can consist of contiguous cells (e.g., A1:B5) or non-contiguous cells (e.g., A1, C1, E1).
  • Ranges are often used to perform operations such as formatting, formula application, or data analysis on multiple cells simultaneously.
  • A range is referenced using the addresses of the first and last cell in the selection, separated by a colon (e.g., A1:D10).

Additional Information

  • Collection of formula: This refers to a set of formulas used in a worksheet but does not define a cell range.
  • Collection of values: This refers to data or numbers in the cells, but it does not explain what a cell range is.
  • Collection of occupied cells: This includes all cells with data but is not the definition of a cell range. A cell range can also include empty cells.
  • Cell range: It can include empty or filled cells based on the user's selection in the spreadsheet.
39

Which of the following cannot be reported as Cyber Crime? 

  1. ((a))

    Threatening someone on social media platform

  2. ((b))

    Theft of a brand new hard disk from a showroom

  3. ((c))

    Sharing of pornographic content online

  4. ((d))

    Entering in someone's online bank account and transferring money from there without his/her consent

Show Answer
Answer: ((b))

Theft of a brand new hard disk from a showroom

The correct answer is Theft of a brand new hard disk from a showroom.

Key Points

  • Cybercrime refers to any criminal activity that involves the internet, computers, or digital systems.
  • Activities that can be classified under cybercrime include hacking, online threats, unauthorized access to someone's account, and sharing illicit content.
  • In this case:
  • Threatening someone on social media, sharing pornographic content online, and accessing someone’s online bank account without consent are all examples of cybercrimes.
  • Theft of a physical item (e.g., a hard disk from a showroom) is not a cybercrime, as it does not involve the misuse of a computer or digital system.

Additional Information

  • Cybercrime Categories: Cybercrime can be categorized into three main types:
  • Computer as a Target: Attacks like hacking, denial of service attacks, or spreading viruses.
  • Computer as a Tool: Using computers to commit crimes like fraud, identity theft, or phishing.
  • Computer as a Communication Medium: Harassment, threats, or sharing illicit content through digital platforms.
  • Physical Crime vs. Cybercrime: Stealing a physical object, such as a hard disk, is considered theft or robbery and falls under traditional criminal law, not cybercrime.
40

What does 's' stand for in https? 

  1. ((a))

    Secure

  2. ((b))

    Security

  3. ((c))

    Stream

  4. ((d))

    Space

Show Answer
Answer: ((a))

Secure

The correct answer is Secure.

Key Points

  • The 'S' in HTTPS stands for Secure.
  • HTTPS (HyperText Transfer Protocol Secure) is an extension of HTTP (HyperText Transfer Protocol).
  • It is used to ensure secure communication over a computer network, especially the internet.
  • HTTPS uses encryption protocols such as SSL (Secure Sockets Layer) or TLS (Transport Layer Security) to secure data exchange.
  • It helps in protecting sensitive information such as passwords, credit card details, and personal data from being intercepted by malicious actors.

Additional Information

  • HTTP (HyperText Transfer Protocol): It is a protocol used for transmitting hypertext over the web, but it does not provide secure communication.
  • SSL/TLS: Secure Sockets Layer and Transport Layer Security are cryptographic protocols that provide end-to-end security of data sent between applications over the internet.
  • Encryption: HTTPS encrypts data so that it becomes unreadable to unauthorized parties, ensuring data confidentiality and integrity.
  • Browser Indication: HTTPS-enabled websites are usually indicated by a padlock symbol in the browser's address bar.

Education and Leadership (40 questions)

41

The proximodistal principle states that development of the body proceeds from: 

  1. ((a))

    head to legs

  2. ((b))

     legs to head

  3. ((c))

    outward to the center of the body

  4. ((d))

    the center of the body outward

Show Answer
Answer: ((d))

the center of the body outward

The proximodistal principle is a fundamental concept in human development, particularly in the study of physical growth and motor development in children. It describes the pattern in which motor skills and body control develop from the center of the body outward toward the extremities. 

Key Points

  • According to this principle, a child first develops control over the central parts of the body such as the torso and shoulders.
  • Gradually, development progresses outward toward the hands, fingers, and legs, allowing for more precise movements.
  • This explains why infants can control their arms before mastering fine finger movements or why gross motor skills appear before fine motor skills.

 Hint

  • The head to legs pattern describes the cephalocaudal principle, which is different from proximodistal development.
  • The legs to head sequence is not observed in typical human development.
  • Outward to the center of the body is the opposite direction of the proximodistal principle and does not reflect how motor skills actually emerge.

Hence, the correct answer is the center of the body outward.

42

Adam's apple is: 

  1. ((a))

    an endocrine gland that releases hormones.

  2. ((b))

    the embryonic outgrowth during prenatal stage.

  3. ((c))

    the protruding part of throat of male adolescents.

  4. ((d))

    the protruding part of throat of female adolescents. 

Show Answer
Answer: ((c))

the protruding part of throat of male adolescents.

Adam's apple is a term commonly used in anatomy and human development, particularly during puberty. It refers to the noticeable protrusion in the front of the neck, which becomes more prominent in males due to hormonal changes. 

Key Points

  • The protruding part of the throat in male adolescents becomes prominent because of the enlargement of the thyroid cartilage during puberty.
  • This growth is more noticeable in males than females due to higher testosterone levels, which makes the voice deeper and gives the characteristic bulge.
  • An endocrine gland that releases hormones refers to structures like the thyroid or pituitary gland, not the Adam's apple.
  • The embryonic outgrowth during the prenatal stage, such as the pharyngeal arches, is unrelated to postnatal throat development.
  • The protruding part of the throat in female adolescents is much less prominent and usually not referred to as an Adam's apple.

Hence, the correct answer is the protruding part of throat of male adolescents.

43

No one taught a 8 months old child to crawl. But one day, the child started crawling. On the part of the child, it shows his/her : 

  1. ((a))

    growth

  2. ((b))

    development

  3. ((c))

    maturation

  4. ((d))

    morphogenesis

Show Answer
Answer: ((c))

maturation

The concepts of growth, development, and maturation are central in understanding human physical and behavioral changes over time.

 Key Points

  • Growth generally refers to measurable physical changes like height and weight, while development encompasses the acquisition of skills, abilities, and functions.
  • Maturation specifically describes the natural unfolding of biological processes that occur with age, independent of formal teaching or training.
  • When an 8-month-old child begins to crawl without being taught, it reflects the natural biological timetable of the body and nervous system. Crawling emerges as the child’s muscles, coordination, and nervous system mature, even without explicit instruction.
  • This ability appears as part of the inherent biological unfolding rather than learned behavior, which aligns directly with the concept of maturation.

 Hint

  • Growth refers only to physical increase in size, which is not what is being described here.
  • Development includes learned behaviors and skill acquisition, which may involve teaching or practice.
  • Morphogenesis is about the formation of structures in the organism, not about the onset of motor skills like crawling.

Hence, the correct answer is maturation.

44

Which one of the following is the correct option ? 

  1. ((a))

    Development and growth are the process and product of maturity.

  2. ((b))

    Development and maturity are the process and product of growth.

  3. ((c))

    Growth and maturity are the process and product of development.

  4. ((d))

    Progress and maturity are the process and product of development

Show Answer
Answer: ((a))

Development and growth are the process and product of maturity.

Growth, development, and maturity are closely related concepts in human development.

Key Points

  • Development represents the ongoing process through which an individual acquires new abilities, skills, and functions over time.
  • Growth is part of this process as the body changes physically and structurally.
  • Maturity is the outcome or product of these processes, representing the full development of physical and functional capabilities.
  • Growth and maturity are distinct concepts, with growth being only a part of development and maturity the end result.
  • Development and maturity cannot be simply linked as process and product of growth because development encompasses more than just physical growth.
  • Progress and maturity is a less precise formulation since “progress” is a broader term not strictly equivalent to growth or development.

Hence, the correct answer is Development and growth are the process and product of maturity.

45

On the part of an individual, the acquisition of values, which the society expects to imbibe and practice, is known as his/her: 

  1. ((a))

    social development

  2. ((b))

    moral development 

  3. ((c))

    emotional development

  4. ((d))

    spiritual development

Show Answer
Answer: ((a))

social development

Human development is multidimensional, encompassing physical, cognitive, emotional, moral, and social aspects. Moral development specifically refers to the process through which an individual learns the difference between right and wrong and internalizes values and ethical standards. 

Key Points

  • When an individual acquires values that society expects them to practice, it reflects the internalization of ethical norms and principles. This is not just about following rules but about developing a sense of right and wrong, fairness, and justice.
  • Moral development shows the person’s capacity to make decisions that align with societal moral expectations.

 Hint

  • Social development involves learning to interact and communicate with others, but it does not necessarily involve moral judgment.
  • Emotional development refers to understanding and managing feelings, not the adoption of societal values.
  • Spiritual development concerns beliefs and practices related to the human spirit or soul, which may or may not include societal moral norms.

Hence, the correct answer is moral development.

46

In class VIII Mathematics, the concept 'Simple Interest is taught first and then the concept 'Compound Interesť is taught. This is in accordance to the: 

  1. ((a))

    Cognitive development of the students

  2. ((b))

    Physical development of the students

  3. ((c))

    Social development of the students

  4. ((d))

    Moral development of the students

Show Answer
Answer: ((a))

Cognitive development of the students

Human learning and teaching are closely linked to the developmental readiness of students.

 Key Points

  • Cognitive development refers to the growth of thinking, reasoning, and problem-solving abilities in learners. In mathematics, the sequencing of concepts is designed to match students’ cognitive capacity, ensuring that foundational ideas are understood before introducing more complex ones.
  • Teaching simple interest before compound interest aligns with students’ cognitive development because simple interest is a basic concept that involves straightforward calculation and understanding.
  • Once students grasp this, they are better prepared to handle the more complex idea of compound interest, which requires higher-order thinking and the ability to apply previous knowledge. This progression ensures that learning builds on existing mental structures, facilitating effective understanding.

 Hint

  • Physical development relates to growth and motor skills, not mathematical reasoning.
  • Social development involves interaction, communication, and social skills, which are not the focus here.
  • Moral development deals with understanding right and wrong, which is unrelated to the order of teaching mathematical concepts.

Hence, the correct answer is cognitive development of the students.

47

In human infants, in comparison to total body length the head constitutes:

  1. ((a))

    12\frac{1}{2}

  2. ((b))

    13\frac{1}{3}

  3. ((c))

    14\frac{1}{4}

  4. ((d))

    ​ 18\frac{1}{8}

Show Answer
Answer: ((c))

14\frac{1}{4}

Human physical growth follows specific patterns, with different parts of the body developing at different rates. In infants, the head is relatively large compared to the rest of the body because the brain and skull develop earlier and faster than other body parts.

Key Points

  • In human infants**, the head constitutes about one-fourth of the total body length.** This relatively large proportion supports rapid brain growth during early life.
  • As the child grows, the rest of the body gradually catches up, and the head becomes proportionally smaller compared to total body length. This explains why infants appear top-heavy with a prominent head compared to their torso and limbs.

Hence, the correct answer is one-fourth.

48

The infants show general excitement to strong stimu stimulation. This is the sign of their : 

  1. ((a))

    metacognitive skills

  2. ((b))

    cognitive growth

  3. ((c))

    emotional behaviour

  4. ((d))

    socialization 

Show Answer
Answer: ((c))

emotional behaviour

Human development encompasses multiple domains, including cognitive, emotional, social, and metacognitive growth. 

Key Points

  • When infants show general excitement to strong stimulation, such as loud sounds, bright lights, or playful interaction, it reflects their emotional responsiveness.
  • This excitement is a basic form of emotional expression and regulation, indicating how the infant experiences joy, surprise, or interest.
  • These reactions are part of their emotional behavior, helping caregivers gauge the child’s feelings and emotional health.

 Hint

  • Metacognitive skills involve self-awareness and regulation of one’s own thinking, which infants have not yet developed.
  • Cognitive growth relates to thinking and problem-solving, not the immediate emotional reaction.
  • Socialization involves interacting with others and learning societal norms, which is broader than simple excitement to stimuli.

Hence, the correct answer is emotional behaviour.

49

With respect to adolescents, which one of the following is a correct statement? 

  1. ((a))

    Their spiritual development is more visible than physical development.

  2. ((b))

    Their cognitive development is more visible than physical development.

  3. ((c))

    Their cognitive development is more visible than social development.

  4. ((d))

    Their physical development is more visible than cognitive development.

Show Answer
Answer: ((d))

Their physical development is more visible than cognitive development.

Adolescence is a period of rapid and noticeable changes across multiple domains of human development, including physical, cognitive, social, emotional, and spiritual growth. 

Key Points

  • In adolescents, physical development is particularly striking because it involves visible changes like increased height, weight, and the development of features such as the Adam’s apple in males and breast development in females.
  • These changes occur rapidly and are easily observed by peers, family, and teachers.
  • Cognitive development, although critical, progresses internally through reasoning, abstract thinking, and problem-solving, making it less outwardly visible.

 Hint

  • Spiritual development occurs internally and is subtle, often not directly observable.
  • Cognitive development is less visible than physical development because thinking processes and intellectual growth cannot be directly seen.
  • Social development, while noticeable in interactions, still does not surpass the visual impact of physical changes during adolescence.

Hence**, the correct answer is their physical development is more visible than cognitive development.**

50

In case of adolescents, the inter personal and intra personal growth patterns show their: 

  1. ((a))

    cognitive development and social development respectively. 

  2. ((b))

    moral development and social development respectively.

  3. ((c))

    emotional development and moral development respectively.

  4. ((d))

    social development and cognitive development respectively.

Show Answer
Answer: ((d))

social development and cognitive development respectively.

Human development during adolescence is multidimensional, involving physical, cognitive, emotional, social, and moral growth.

 Key Points

  • Interpersonal growth refers to the ability to interact effectively with others, forming relationships and understanding social norms, which is a key aspect of social development. Intrapersonal growth, on the other hand, involves self-awareness, self-reflection, and understanding one’s own thoughts and emotions, which are closely linked to cognitive development.
  • Interpersonal growth in adolescents reflects their social development because it shows how they form friendships, resolve conflicts, and communicate with peers and adults.
  • Intrapersonal growth shows their cognitive development, as it involves thinking about one’s own beliefs, planning, problem-solving, and decision-making.

 Hint

  • Moral development is related to understanding right and wrong but is not specifically indicated by interpersonal or intrapersonal growth.
  • Emotional development involves feelings and emotional regulation, which may influence but do not fully define these growth patterns.

Hence**, the correct answer is social development and cognitive development respectively.**

51

In language class of adolescent students the teacher uses an English idiom 'A Leopard can't change his spots' which means 'a person cannot change his/her basic nature'. The teacher thinks that : 

  1. ((a))

    Students cannot understand it as adolescence is a stage where only concrete thinking dominates.

  2. ((b))

    Students may imagine the impossible as they have developed abstract thinking so they can understand it.

  3. ((c))

    Students may understand it as they can use symbolic thinking to derive its meaning.

  4. ((d))

    Students cannot understand it as their critical thinking proves that in reality the idiom and it's meaning don't synchronize.

Show Answer
Answer: ((c))

Students may understand it as they can use symbolic thinking to derive its meaning.

Adolescence is a stage of cognitive development where thinking shifts from concrete to more abstract and complex forms. According to Piaget, during this stage, individuals develop the ability to reason hypothetically, understand symbols, and think beyond immediate experiences. 

Key Points

  • When a teacher uses the idiom “A leopard can’t change his spots,” adolescents are capable of interpreting its figurative meaning that a person’s basic nature does not change because they can engage in symbolic thinking.
  • They are able to go beyond the literal words and derive abstract or symbolic meaning, reflecting their developing cognitive abilities. This shows that adolescents can handle language that conveys concepts indirectly through symbols or cultural expressions.

 Hint

  • It is not accurate to say students cannot understand it due to dominance of concrete thinking, because by adolescence, abstract thinking is well-developed.
  • Imagining the impossible may occur, but the key factor is their ability to use symbols to interpret meaning, not mere imagination.
  • Critical thinking does not prevent understanding the idiom; rather, it may help evaluate its application, but it does not block comprehension.

Hence, the correct answer is students may understand it as they can use symbolic thinking to derive its meaning.

52

The term 'society' is rooted in the word 'societas' which is a/an:

  1. ((a))

    African word

  2. ((b))

    Chinese word

  3. ((c))

    Greek word

  4. ((d))

    Latin word

Show Answer
Answer: ((d))

Latin word

The study of society and its origins often involves looking at the etymology of the term.

 Key Points

  • The word “society” comes from the Latin word “societas,” which refers to fellowship, association, or companionship.
  • This origin reflects the basic human tendency to form groups, communities, and relationships, emphasizing cooperation and collective living.
  • “Societas” in Latin specifically conveys the idea of people coming together for common purposes, mutual support, and organized interaction.
  • This aligns with the modern sociological understanding of society as a complex system of relationships and institutions. It explains why the term society carries connotations of connectedness and group living rather than just a collection of individuals.

Hence, the correct answer is Latin word.

53

Who defined the word 'community' as a group established by men having shared values ? 

  1. ((a))

    Comte

  2. ((b))

    Marx

  3. ((c))

    Aristotle

  4. ((d))

    Durkheim

Show Answer
Answer: ((a))

Comte

The concept of community has been central to sociology and philosophy, as it helps explain how individuals come together to form social groups with shared interests, norms, and values. 

Key Points

  • Auguste Comte, often regarded as the father of sociology, focused on the structures of society and the ways in which human beings organize themselves.
  • He emphasized that a community is not merely a collection of individuals but a group established by humans who share common values and norms, which guide their interactions and maintain social order.
  • This aligns directly with the idea of community being formed through shared human values rather than just physical proximity or economic relations.

 Hint

  • Karl Marx, in contrast, analyzed communities mainly in terms of class relations and economic structures rather than shared moral or cultural values.
  • Aristotle discussed the community from a philosophical and political perspective, focusing on the polis and the role of citizens in achieving a good life.
  • Émile Durkheim studied community in terms of social cohesion and collective consciousness, emphasizing the functional aspects of society.

Hence, the correct answer is Comte.

54

In the context of socialization, which one of the following is the most appropriately correct statement? 

  1. ((a))

    In some cultures, secondary socialization may precede primary socialization.

  2. ((b))

    Primary socialization and secondary socialization run parallel to each other.

  3. ((c))

    Secondary socialization takes place only after primary socialization.

  4. ((d))

    Primary socialization and secondary socialization follow an entirely different trajectory.

Show Answer
Answer: ((a))

In some cultures, secondary socialization may precede primary socialization.

Socialization is the lifelong process through which individuals learn the norms, values, behaviors, and roles necessary to participate in society. It is generally categorized into primary socialization, which occurs in early childhood within the family, and secondary socialization, which happens later through schools, peer groups, and broader social institutions. 

Key Points

  • Primary socialization typically comes first, providing the child with foundational behaviors and norms, in some cultural contexts, experiences outside the family such as interactions in early childhood programs or communal activities may introduce elements of secondary socialization before certain primary socialization aspects are fully established.
  • This shows that the sequence is not always strictly linear and can vary depending on cultural practices and societal structures.

 Hint

  • The idea that primary and secondary socialization run strictly parallel is less accurate because early childhood experiences generally have a foundational role.
  • Secondary socialization taking place only after primary socialization overlooks cultural variations where children may be exposed to organized societal norms before completing initial family-based learning.
  • Suggesting entirely different trajectories fails to capture the interconnected nature of these socialization processes.

Hence, the correct answer is In some cultures, secondary socialization may precede primary socialization.

55

The adverse situations like COVID-19 pandemic have led to the: 

  1. ((a))

    increase in enrolment in formal education.

  2. ((b))

    increase in home schooling.

  3. ((c))

    decrease in enrolment in non-formal education.

  4. ((d))

    increase in brain drain.

Show Answer
Answer: ((b))

increase in home schooling.

Adverse situations such as the COVID-19 pandemic have had a profound impact on education systems worldwide. School closures, social distancing measures, and restrictions on gatherings disrupted traditional classroom learning, forcing educators, parents, and students to adapt rapidly.  

Key Points

  • During the pandemic, many families turned to home-based education to ensure continuity of learning when schools were closed.
  • This led to a significant increase in home schooling, with parents taking a more active role in guiding their children’s education or using online learning platforms to compensate for the lack of formal school instruction.
  • It reflects a shift in educational practices in response to extraordinary circumstances rather than a change in formal school enrolment trends.

 Hint

  • An increase in enrolment in formal education was not observed as schools were largely closed.
  • Non-formal education programs also faced disruptions, making a decrease in enrolment more context-specific but not the primary global trend.
  • The notion of brain drain is unrelated to immediate educational adaptations during the pandemic.

Hence, the correct answer is increase in home schooling.

56

Why is curriculum important for the teachers? 

  1. ((a))

    Establishes responsibilities and accountability

  2. ((b))

    Acts as a control device

  3. ((c))

    Develops understanding about preservation of environment

  4. ((d))

    Indicates how the external sources should be utilized for the benefits of the students

Show Answer
Answer: ((a))

Establishes responsibilities and accountability

Curriculum is a structured plan of learning experiences designed to achieve specific educational goals. For teachers, it serves as a guide for what to teach, how to teach, and the desired outcomes of the teaching-learning process.

Key Points

  • For teachers, curriculum is crucial because it clearly establishes their responsibilities and accountability. It defines what they are expected to teach, the skills and knowledge students should acquire, and the standards they need to uphold.
  • This helps teachers plan lessons, assess student progress, and reflect on their own professional practice, ensuring that educational goals are systematically achieved.

​ Hint

  • While it can indirectly guide how external resources are used, its primary function is not just about resource utilization.
  • Acting as a control device refers more to administrative oversight rather than pedagogical guidance.
  • Developing understanding about environmental preservation may be a component of specific curricula but does not capture the overarching importance of curriculum for teachers’ roles.

Hence**, the correct answer is establishes responsibilities and accountability.**

57

Which one of the following may not be an important principle of curriculum organisation? 

  1. ((a))

    Principle of child centeredness

  2. ((b))

    Principle of creativity

  3. ((c))

    Principle of self learning

  4. ((d))

    Principle of flexibility

Show Answer
Answer: ((c))

Principle of self learning

Curriculum organization is guided by principles that ensure learning is effective, meaningful, and suited to the needs of learners. These principles help in structuring content, learning experiences, and instructional strategies so that students can engage actively, develop skills, and achieve educational goals. 

Key Points

  • While child centeredness, creativity, and flexibility are fundamental principles focusing on the learner’s needs, fostering innovation, and allowing adaptation to changing circumstances—self learning, though valuable, is more of a learning strategy than an overarching principle of curriculum organization.
  • Curriculum principles are intended to guide the overall design and structure, rather than prescribing specific methods for individual learning.
  • Principles like child centeredness ensure relevance and engagement, creativity promotes innovative thinking, and flexibility allows the curriculum to respond to societal and learner needs. Self learning can be encouraged within the curriculum but does not define its organizational framework.

Hence, the correct answer is principle of self learning.

58

Which one of the following is not an element of experiential learning cycle ? 

  1. ((a))

    Concrete experience

  2. ((b))

    Reflective observation

  3. ((c))

    Critical analysis

  4. ((d))

    Active experimentation

Show Answer
Answer: ((c))

Critical analysis

Experiential learning is a process through which learners acquire knowledge and skills by actively engaging in experiences and reflecting on them. David Kolb’s experiential learning cycle outlines a continuous process where learning occurs through a sequence of stages, allowing learners to connect theory with practice and improve their understanding through reflection and experimentation.

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Key Points

  • The experiential learning cycle consists of concrete experience, where learners actively engage in a task; reflective observation, where they reflect on the experience; and active experimentation, where they test their insights in new situations.
  • Critical analysis, while useful in evaluating experiences, is not explicitly identified as a separate stage in Kolb’s model. It may be part of reflection but is not formally a component of the cycle itself.
  • Concrete experience provides hands-on engagement, reflective observation allows understanding and insight, and active experimentation applies learning in practical contexts.
  • Critical analysis is a skill used during reflection but does not form a distinct stage of the experiential learning process.

Hence, the correct answer is critical analysis.

59

Which one of the following may not be accomplished by students through 'self assessment'? 

  1. ((a))

    Reflection on their own learning

  2. ((b))

    Consolidation of their learning through dialogue

  3. ((c))

    Skills in meta cognition

  4. ((d))

    Identification of the areas of their strength and of their weakness

Show Answer
Answer: ((b))

Consolidation of their learning through dialogue

Self-assessment is a process in which students evaluate their own learning, performance, and understanding. It encourages learners to take responsibility for their progress, develop critical thinking, and become more aware of their strengths and areas needing improvement.

 Key Points

  • Through self-assessment, students can reflect on their own learning, identify areas of strength and weakness, and develop skills in metacognition, which help them plan, monitor, and evaluate their learning strategies.
  • However, consolidation of learning through dialogue typically requires interaction with teachers or peers and involves discussion, feedback, and collaborative understanding, which goes beyond individual self-assessment.
  • Reflection allows learners to internalize their experiences, metacognition enhances awareness of learning processes, and identifying strengths and weaknesses helps set personal learning goals.
  • Dialogue-based consolidation is more of a social learning process rather than an outcome of self-assessment.

Hence, the correct answer is consolidation of their learning through dialogue.

60

Which one of the following is not an advantage of using textbook in classroom teaching learning process? 

  1. ((a))

    A useful teaching aid in the hands of a teachers

  2. ((b))

    Encourages convergent thinking among learners through its chapters and exercises

  3. ((c))

    Provides guidelines for students evaluation

  4. ((d))

    Help teachers to maintain logical reference of content matter

Show Answer
Answer: ((b))

Encourages convergent thinking among learners through its chapters and exercises

Textbooks are a central resource in classroom teaching, providing structured content, exercises, and guidance for both teachers and students. They serve as a reference point, help organize lessons, and support the evaluation of learning outcomes. 

Key Points

  • Textbooks are indeed useful as teaching aids, help teachers maintain a logical sequence of content, and provide guidelines for evaluating students’ learning.
  • However, they may not inherently encourage convergent thinking, which involves finding multiple solutions or creative approaches to problems.
  • Textbooks are generally structured with predefined content and exercises, which may limit open-ended exploration and creative or divergent thinking.
  • They assist teachers in planning lessons, maintaining content order, and assessing student performance.
  • Convergent thinking and creativity in learners usually require additional instructional strategies beyond merely following textbook chapters.

Hence, the correct answer is encourages convergent thinking among learners through its chapters and exercises.

61

Which one of the following may not be considered as a main characteristic of multimedia system? 

  1. ((a))

    Social loafing

  2. ((b))

    Can be used as an interactive device

  3. ((c))

    Requires judiciously planned usage

  4. ((d))

    Sharpens skills in problem solving and decision making areas

Show Answer
Answer: ((a))

Social loafing

Multimedia systems combine text, audio, images, animation, and video to create interactive and engaging learning experiences. They are widely used in education, training, and communication because they can enhance understanding, stimulate interest, and develop higher-order thinking skills.

 Key Points

  • Effective use of multimedia requires careful planning and thoughtful integration into the learning process.
  • Multimedia systems are interactive tools that can sharpen problem-solving and decision-making skills when used appropriately. Their use must be judiciously planned to align with learning objectives and avoid distractions.
  • However, social loafing, which refers to reduced individual effort when working in a group, is a social phenomenon unrelated to the inherent characteristics of multimedia systems.
  • Interactivity allows learners to engage actively with content, planning ensures effectiveness, and cognitive benefits enhance learning outcomes.
  • Social loafing is a behavioral issue in group settings, not a feature of multimedia technology itself.

Hence, the correct answer is social loafing.

62

Which of the following is an incorrect statement? 

  1. ((a))

    Extended response type item is an essay type item.

  2. ((b))

    In multiple choice item the incorrect option are known as distracters.

  3. ((c))

    Objective type of item are more preferable in measuring the creative ability of students.

  4. ((d))

    Matching type of item is a form of multiple choice type.

Show Answer
Answer: ((c))

Objective type of item are more preferable in measuring the creative ability of students.

Assessment items are designed to evaluate different levels of learning, ranging from knowledge recall to higher-order thinking skills. They can be broadly categorized into objective-type items, which have specific correct answers, and extended-response items, which require students to elaborate or explain their understanding. 

Key Points

  • Extended-response items, such as essays, allow students to express ideas in depth, while multiple-choice items use distracters to test recognition and understanding.
  • Matching items are a type of objective question where students pair related items, making them similar in structure to multiple-choice questions.
  • However, objective-type items, which are generally designed for quick recall or recognition, are not ideal for measuring creative ability, which requires open-ended responses, critical thinking, and original expression.
  • Objective items are efficient for testing factual knowledge but do not capture creativity.
  • Extended-response items support deeper thought, and matching and multiple-choice formats are suitable for evaluating comprehension and recognition skills.

Hence, the correct answer is objective type of item are more preferable in measuring the creative ability of students.

63

Which of the following is not a difficulty associated with group learning? 

  1. ((a))

    Absence systematic approach to work 

  2. ((b))

    Easy identification and correction of errors

  3. ((c))

    Lack of adequate coordination among participants

  4. ((d))

    Pressures on individual learners to conform on the issue having discussed in the group

Show Answer
Answer: ((b))

Easy identification and correction of errors

Group learning is an instructional approach where students work collaboratively to achieve shared learning goals. While it promotes discussion, critical thinking, and social skills, it also comes with challenges. Understanding these difficulties helps teachers design group activities that maximize benefits while minimizing potential drawbacks.

Key Points

  • Difficulties in group learning often include the absence of a systematic approach, lack of coordination among participants, and social pressures on individuals to conform to group opinions.
  • However, easy identification and correction of errors is actually an advantage of group learning, as peers can provide immediate feedback and support each other in understanding mistakes. This process enhances collective learning and problem-solving rather than being a difficulty.
  • Other challenges involve managing participation, ensuring fairness, and maintaining focus on learning objectives. Peer interaction can be both a strength and a challenge depending on how the group is structured and facilitated.

Hence, the correct answer is easy identification and correction of errors.

64

Which one is not a role of the teachers in construction of knowledge of students ? 

  1. ((a))

    Allowing students to ask questions and encouraging them to raise intelligent questions

  2. ((b))

    Discouraging self analysis and self assessment

  3. ((c))

    Fostering reflective practice

  4. ((d))

    Supporting cooperative and collaborative learning in the classroom

Show Answer
Answer: ((b))

Discouraging self analysis and self assessment

In a constructivist approach to learning, teachers act as facilitators who guide students in constructing their own knowledge rather than simply transmitting information.

Key Points

  • The teacher’s role involves creating an environment where learners actively engage, reflect, and collaborate to build understanding, critical thinking, and problem-solving skills.
  • Teachers encourage students to ask questions, promote self-analysis and self-assessment, foster reflective practice, and support cooperative and collaborative learning.
  • Discouraging self-analysis and self-assessment, however, goes against the principles of knowledge construction, as these activities help learners evaluate their own understanding, identify gaps, and take ownership of their learning.
  • Encouraging inquiry and collaboration enhances engagement, while reflective practice deepens comprehension.
  • Preventing self-assessment would hinder students’ ability to internalize knowledge and become independent learners.

Hence, the correct answer is discouraging self analysis and self assessment.

65

'Learner centered approach' is not characterized by: 

  1. ((a))

    Learning by doing

  2. ((b))

    Both individual and group learning

  3. ((c))

    Learning and memorization of textual questions

  4. ((d))

    Democratic classroom environments 

Show Answer
Answer: ((c))

Learning and memorization of textual questions

The learner-centered approach emphasizes active engagement, critical thinking, and meaningful learning experiences. It shifts the focus from teacher-led instruction to student-driven exploration, encouraging learners to construct knowledge through interaction, experimentation, and collaboration. 

Key Points

  • Learner-centered classrooms prioritize learning by doing, support both individual and group learning, and foster democratic environments where students have a voice in their learning.
  • However, learning that focuses primarily on memorization of textual questions is teacher-centered, as it emphasizes rote learning rather than understanding, application, or critical thinking.
  • Active engagement, collaboration, and democratic participation are key features, whereas rote memorization limits learner involvement and reduces opportunities for constructing knowledge.

Hence, the correct answer is learning and memorization of textual questions.

66

In a teaching learning situation four stages are being followed:

  1. Identification of problems
  2. Experimentation and observation
  3. Problem solving
  4. Evaluation

Which of the following method is being applied ?

  1. ((a))

    Project Method

  2. ((b))

    Problem solving Method

  3. ((c))

    Discovery Method

  4. ((d))

    Inductive Method

Show Answer
Answer: ((b))

Problem solving Method

Teaching-learning methods provide structured ways for students to acquire knowledge, develop skills, and engage in critical thinking. Different methods emphasize various approaches, such as guided inquiry, experimentation, and reflection, to promote active learning and problem-solving abilities.  

Key Points

  • The sequence described—identifying problems, experimentation and observation, problem solving, and evaluation—aligns with the problem-solving method.
  • This method encourages learners to recognize an issue, explore possible solutions through investigation, apply reasoning to resolve it, and finally evaluate the outcome.
  • It emphasizes analytical thinking and structured inquiry rather than merely memorizing content.

 Hint

  • Project method typically involves extended investigations on a topic, discovery method emphasizes uncovering concepts through guided exploration, and inductive method focuses on deriving general principles from specific observations.

Hence, the correct answer is problem-solving method.

67

Which of the following is not a strength of portfolio ? 

  1. ((a))

    Development of skill among students in evaluating the strength and weakness of their own work

  2. ((b))

    Creates opportunity to collaborate and reflect on students progress. 

  3. ((c))

    Parents have rare opportunity to assess the performance of their children.

  4. ((d))

    Helps students to take responsibility for setting goals and evaluating their progress

Show Answer
Answer: ((c))

Parents have rare opportunity to assess the performance of their children.

A portfolio is a systematic collection of a student’s work over time that demonstrates learning, achievements, and areas for improvement. It serves as both a learning and assessment tool, encouraging reflection, goal-setting, and active participation in evaluating one’s own progress.

 Key Points

  • Portfolios also facilitate communication between teachers, students, and parents regarding learning outcomes.
  • Portfolios help students evaluate the strengths and weaknesses of their work, reflect on their progress, and take responsibility for setting goals.
  • They also create opportunities for collaboration and ongoing dialogue about learning.
  • However, the idea that parents have only a rare opportunity to assess their child’s performance is inaccurate, as portfolios are specifically designed to provide regular, accessible insights into student learning for both teachers and parents.
  • Reflection, goal-setting, and self-evaluation are key strengths, whereas limiting parental access does not align with the purpose of a portfolio.

Hence, the correct answer is parents have rare opportunity to assess the performance of their children.

68

Role of teacher in 'trans disciplinary integration' is that of a : 

  1. ((a))

    Co-learner

  2. ((b))

    Facilitator

  3. ((c))

    Specialist

  4. ((d))

    Generalist

Show Answer
Answer: ((b))

Facilitator

Transdisciplinary integration involves connecting knowledge and skills across multiple subjects to address real-world problems or themes. In this approach, learning is not confined to a single discipline; instead, students explore concepts in an interconnected manner.

 Key Points

  • Teachers play a crucial role in guiding this process, helping learners see relationships between disciplines and apply knowledge meaningfully.
  • In transdisciplinary integration, the teacher acts as a facilitator, supporting students as they explore, inquire, and construct understanding across subject boundaries.
  • The teacher guides discussions, provides resources, and encourages critical thinking, rather than being the sole source of knowledge.
  • Acting as a co-learner or specialist is secondary, as the emphasis is on enabling students to make connections themselves.

Hence, the correct answer is facilitator.

69

What should be the basic determinant of a good classroom discussion? 

  1. ((a))

    Skill of the teacher's

  2. ((b))

    Teacher's mastery our the topic

  3. ((c))

    Content being discussed

  4. ((d))

    Unity of purpose and interest in the class

Show Answer
Answer: ((d))

Unity of purpose and interest in the class

Classroom discussion is an essential instructional strategy that promotes critical thinking, idea exchange, and active learning. Its effectiveness depends not only on the teacher’s skills or content knowledge but also on the engagement, motivation, and shared focus of the learners.

 Key Points

  • A productive discussion requires a conducive environment where participants are genuinely interested and aligned in purpose.
  • While the teacher’s skill and mastery of the topic are important, the basic determinant of a good discussion is the unity of purpose and interest among students.
  • When students share a common focus and are genuinely interested in the topic, discussions become meaningful, interactive, and productive. Without this shared engagement, even a skilled teacher or well-prepared content may fail to generate meaningful dialogue.
  • Content quality and teacher expertise support discussion, but the collective interest and purposeful participation of students drive its success.
  • A discussion thrives when learners are motivated, attentive, and collaboratively exploring ideas.

Hence, the correct answer is unity of purpose and interest in the class.

70

Objectives of education are not helpful in: 

  1. ((a))

    Understanding child development

  2. ((b))

    Selecting instructional materials

  3. ((c))

    Designing learning experience

  4. ((d))

    Preparing evaluation tools

Show Answer
Answer: ((a))

Understanding child development

Educational objectives serve as clear statements of what learners are expected to achieve through instruction. They provide direction for curriculum design, lesson planning, instructional strategies, and assessment. 

Key Points

  • Objectives of education guide understanding of child development by indicating the skills, knowledge, and attitudes learners should acquire at various stages.
  • They assist in selecting instructional materials and designing learning experiences that align with these goals. They also help in preparing evaluation tools to measure whether learning outcomes have been achieved.
  • However, they do not directly contribute to understanding the developmental psychology of the child itself; rather, they focus on planning and assessing learning.
  • While objectives influence teaching and assessment, they are not a primary tool for analyzing or understanding a child’s growth patterns or developmental stages. They are designed to structure learning experiences rather than study child development scientifically.

Hence, the correct answer is understanding child development.

71

In modern context the best mental health of students and teachers can be ensured by: 

  1. ((a))

    Yogasana and Pranayam

  2. ((b))

    Physiotheraphy

  3. ((c))

    Mathematical and mental exercises

  4. ((d))

    Organizing social gatherings

Show Answer
Answer: ((a))

Yogasana and Pranayam

Mental health in educational settings is crucial for both students and teachers, as it affects learning, teaching effectiveness, and overall well-being.

Key Points 

  • Modern approaches to mental health emphasize holistic practices that balance physical, mental, and emotional wellness, helping individuals manage stress, improve concentration, and enhance resilience.
  • Practices like Yogasana and Pranayama are particularly effective because they combine physical postures, controlled breathing, and mindfulness, which reduce stress, improve focus, and promote emotional stability.
  • These techniques support both mental and physical health, making them well-suited for sustaining overall well-being in the school environment.
  • Yogasana and Pranayama integrate mind-body practices, enhance concentration, and reduce anxiety, making them highly effective for educational settings. Other activities may have benefits but do not comprehensively address mental health.
  • Physiotherapy mainly addresses physical rehabilitation, mathematical exercises enhance cognition but not emotional wellness, and social gatherings may promote interaction but do not systematically improve mental health.

Hence, the correct answer is Yogasana and Pranayam.

72

The right of persons with disability Act came in which year? 

  1. ((a))

    2014

  2. ((b))

     2016

  3. ((c))

    2018

  4. ((d))

    2020

Show Answer
Answer: ((b))

 2016

The Rights of Persons with Disabilities Act is a significant legislation in India aimed at protecting the rights and ensuring the inclusion of persons with disabilities in all aspects of society, including education, employment, and accessibility.

 Key Points

  • It replaced the earlier Persons with Disabilities Act of 1995 to align with the United Nations Convention on the Rights of Persons with Disabilities (UNCRPD), reflecting a more progressive approach toward disability rights.
  • This Act defines various types of disabilities, emphasizes equal opportunities, and mandates accessibility, non-discrimination, and inclusive education. It also outlines the responsibilities of the government, educational institutions, and employers to facilitate participation and empowerment of persons with disabilities.
  • The legislation came into effect in 2016, marking a key milestone in promoting rights and inclusion for differently-abled individuals.

Hence, the correct answer is 2016.

73

In terms of education progress which one of the following groups is the largest ? 

  1. ((a))

    Tribals

  2. ((b))

    Schedule castes

  3. ((c))

    Slum dwellers

  4. ((d))

    Girls

Show Answer
Answer: ((d))

Girls

Educational progress varies across different social groups due to historical, economic, and social factors. Understanding which groups constitute the largest population in terms of education helps policymakers and educators target interventions effectively. 

Key Points

  • Among the given groups, girls represent the largest demographic in the context of education because they comprise roughly half of the total student population.
  • While tribal populations, scheduled castes, and slum dwellers are significant in number, they are subsets of the overall population, whereas girls span all social, economic, and geographic categories.
  • Educational policies increasingly focus on ensuring gender parity and improving girls’ enrollment and retention across all levels of schooling.

Other groups, such as tribals and scheduled castes, are important targets for inclusive education programs, and slum dwellers face localized challenges, but in sheer numbers, girls form the largest group in the educational landscape.

Hence, the correct answer is girls.

74

Which one of the following can be easily handled by school teachers ? 

  1. ((a))

    Autistic child

  2. ((b))

    A child with an IQ of 72

  3. ((c))

    A child with dyscalculia

  4. ((d))

    A psychotic child

Show Answer
Answer: ((b))

A child with an IQ of 72

In inclusive education, teachers often encounter students with diverse learning needs and disabilities. The ability of a teacher to handle a child depends on the severity of the condition, the support required, and the teacher’s training. 

Key Points

  • A child with an IQ of 72 falls in the borderline range of intellectual functioning. Such a child can often be supported effectively in a regular classroom with adjustments, remedial teaching, and individualized attention.
  • Teachers can use simplified instructions, peer support, and structured learning activities to help these students achieve academic and social goals.
  • In contrast, children with autism, dyscalculia, or psychosis may require specialized therapies, individualized education plans, or professional mental health interventions that go beyond typical classroom strategies.

Hence**, the correct answer is a child with an IQ of 72.**

75

Among the following options, which one is easier for a school seeking partnership? 

  1. ((a))

    Neighboring schools

  2. ((b))

    Industry

  3. ((c))

    Parents and community

  4. ((d))

    Adjoining government offices

Show Answer
Answer: ((c))

Parents and community

Partnerships in education help schools enhance learning opportunities, access resources, and foster community engagement. The ease of forming partnerships depends on accessibility, shared interests, and the level of collaboration required. 

Key Points

  • Parents and the community are the most accessible and cooperative partners for a school. They are directly invested in the students’ education, can support classroom activities, contribute resources, and participate in school programs.
  • Their involvement requires minimal formal procedures compared to industries or government offices, which may involve bureaucratic processes, formal agreements, and alignment of objectives.
  • Collaborating with parents and community members promotes active involvement, mutual support, and shared responsibility in education, making it the most practical first step for partnership.
  • Neighboring schools may collaborate academically, but community and parental engagement is generally easier to initiate and sustain.

Hence, the correct answer is parents and community.

76

Higher education institutions can develop the best partnership with schools by 

  1. ((a))

    training school teachers.

  2. ((b))

    organizing competency based activities for school teachers.

  3. ((c))

    sharing their physical and human resources.

  4. ((d))

    selecting best students from schools and giving them advanced learning material.

Show Answer
Answer: ((b))

organizing competency based activities for school teachers.

Partnerships between higher education institutions and schools can enhance the quality of education by providing expertise, resources, and professional development. Effective collaboration helps bridge gaps in curriculum, teaching skills, and student learning experiences, benefiting both teachers and students.

<br>

Key Points

  • Higher education institutions can develop the best partnerships with schools by organizing competency-based activities for school teachers.
  • Such programs build teachers’ skills, update their knowledge, and improve instructional practices, which directly impacts classroom learning.
  • Training alone or merely sharing resources may not ensure practical improvement, and selecting top-performing students for advanced materials benefits only a few rather than strengthening the overall school-teacher ecosystem.
  • Competency-based activities focus on enhancing teachers’ effectiveness, enabling sustainable improvements in student outcomes and fostering a collaborative relationship between institutions.

Hence, the correct answer is organizing competency based activities for school teachers.

77

Which one of the following can best develop the spirit of enquiry and awareness among learners at secondary school level? 

  1. ((a))

    Parent teacher associations

  2. ((b))

    In service programmes for teachers

  3. ((c))

    Hobby clubs

  4. ((d))

    Long duration science experiments

Show Answer
Answer: ((c))

Hobby clubs

Developing a spirit of enquiry and awareness among secondary school learners is essential for fostering critical thinking, curiosity, and independent problem-solving.

 Key Points

  • Educational strategies that actively engage students in exploration, hands-on activities, and collaborative learning are most effective in cultivating these qualities.
  • Hobby clubs provide students with opportunities to explore their interests, engage in practical activities, ask questions, and experiment in a supportive environment.
  • These clubs encourage curiosity, creativity, and sustained engagement, allowing learners to develop inquiry skills and awareness about various topics.
  • Hobby clubs integrate learning with personal interests, promoting active participation, exploration, and questioning, which are key to nurturing a spirit of enquiry.
  • In contrast, parent-teacher associations mainly involve administrative and community matters, in-service programs focus on teacher development, and long-duration science experiments, while valuable, are limited in scope and may not engage all students consistently.

Hence, the correct answer is hobby clubs.

78

Which one of the following combination can best fulfill the objectives of conducting school assembly?

(i) Punishing naughty students

(ii) Everyday reading some part of a classic book

(iii) Physical Fitness exercises

(iv) Sharing decisions of PTA meetings

(v) Addressing general issues of the school

  1. ((a))

    (ii), (iii) and (v)

  2. ((b))

    (i), (iii) and (v)

  3. ((c))

    (i), (ii) and (iii)

  4. ((d))

    (ii), (iii) and (iv)

Show Answer
Answer: ((a))

(ii), (iii) and (v)

School assemblies are an integral part of the daily routine, designed to foster discipline, moral values, awareness, and a sense of community among students. They provide opportunities for collective learning, sharing information, promoting physical well-being, and reinforcing the school’s ethos. 

Key Points

  • Reading a part of a classic book encourages intellectual growth and moral reflection, physical fitness exercises promote health and energy, and addressing general school issues helps in building awareness and a sense of responsibility.
  • Activities like punishing students are disciplinary rather than developmental, and sharing PTA decisions is primarily administrative, not central to the objectives of an assembly.
  • By combining intellectual enrichment, physical activity, and awareness of school matters, assemblies can actively contribute to students’ holistic development and school community cohesion.

Hence, the correct answer is (ii), (iii) and (v).

79

Which Committee talked of education for humane and enlightened society ? 

  1. ((a))

    Raghu Rajan Committee

  2. ((b))

    Acharya Ram Murti Committee

  3. ((c))

    Yashpal Commitee

  4. ((d))

    Acharya Narendra Dev Committee

Show Answer
Answer: ((c))

Yashpal Commitee

Various educational committees in India have been established to review and recommend policies for improving the quality, relevance, and equity of education. These committees often focus on linking education with societal needs, human values, and national development goals. 

Key Points

  • The Yashpal Committee emphasized education that fosters a humane and enlightened society. It advocated for reducing rote learning, promoting creativity, critical thinking, and value-based education, and integrating knowledge across disciplines to prepare students for responsible citizenship.
  • Other committees like Raghu Rajan, Acharya Ram Murti, and Acharya Narendra Dev focused on financial, administrative, or structural aspects of education rather than explicitly promoting a vision of humane and enlightened society.
  • The emphasis was on holistic development, nurturing ethical values, and fostering intellectual curiosity, all aimed at creating a compassionate and informed citizenry.

Hence, the correct answer is Yashpal Committee.

80

Which one of the following does not belong to knowledge domain ? 

  1. ((a))

    Respecting

  2. ((b))

    Analysing

  3. ((c))

    Evaluating

  4. ((d))

    Informing

Show Answer
Answer: ((a))

Respecting

In educational theory, learning is often categorized into different domains: cognitive (knowledge), affective (attitudes and values), and psychomotor (skills). The cognitive domain focuses on mental skills such as recalling, understanding, analyzing, and evaluating information. 

Key Points

  • Analyzing, evaluating, and informing are all activities associated with the cognitive or knowledge domain, involving mental processing, critical thinking, and communication of information.
  • Respecting, however, is related to the affective domain as it involves attitudes, values, and emotional responses rather than purely intellectual activity.
  • Cognitive objectives target understanding, reasoning, and decision-making, whereas affective objectives target values, feelings, and ethical behavior. Recognizing this distinction helps in effective curriculum design and assessment.

Hence, the correct answer is respecting.

Subject Specific (100 questions)

81

A = {1, 2, 3, 4, 5} and the relation R is given by R=(x,y):x+y8,xA,yAR = {(x, y) : x+y \ge 8, x \in A, y \in A} then the set of ordered pairs in R are:

  1. ((a))

    {(4, 5), (5, 4), (5, 5)}

  2. ((b))

    {(4, 4), (4, 5), (5, 3), (5, 5)}

  3. ((c))

    {(3, 5), (4, 4), (4, 5), (5, 3), (5, 4), (5, 5)}

  4. ((d))

    {(4, 5), (5, 4)}

Show Answer
Answer: ((c))

{(3, 5), (4, 4), (4, 5), (5, 3), (5, 4), (5, 5)}

Calculation:

Given set: A = {1, 2, 3, 4, 5}

Relation: use R=(x,y):x+y8,xA,yAR = {(x, y) : x + y \ge 8, x ∈ A, y ∈ A}

For x = 1: use 1+y8    y71 + y \ge 8 \implies y \ge 7. No yAy ∈ A satisfies this.

For x = 2: use 2+y8    y62 + y \ge 8 \implies y \ge 6. No yAy ∈ A satisfies this.

For x = 3: use 3+y8    y53 + y \ge 8 \implies y \ge 5. The only yAy ∈ A is y=5.

    \impliesPair is (3, 5).

For x = 4: use 4+y8    y44 + y \ge 8 \implies y \ge 4. The yAy ∈ A are y=4, 5.

⇒​  Pairs are (4, 4), (4, 5).

For x = 5: use 5+y8    y35 + y \ge 8 \implies y \ge 3. The y ∈ A are y=3, 4, 5.

⇒​  Pairs are (5, 3), (5, 4), (5, 5).

Combining all the pairs gives the set R:

use R=(3,5),(4,4),(4,5),(5,3),(5,4),(5,5)R = {(3, 5), (4, 4), (4, 5), (5, 3), (5, 4), (5, 5)}

Hence option 3 is correct

82

The domain of the function f given by f(x)=x2+2x+1x2x6f(x)=\frac{x^2+2x+1}{x^2-x-6}

  1. ((a))

    R - {- 2, 3} 

  2. ((b))

    R - {- 3, - 2}

  3. ((c))

    R - {- 3, 2}

  4. ((d))

    R - {2, 3}

Show Answer
Answer: ((a))

R - {- 2, 3} 

Calculation:

Given the function: use f(x)=x2+2x+1x2x6f(x) = \frac{x^2+2x+1}{x^2-x-6}

The function is undefined when the denominator is zero. Let Q(x) be the denominator.

Q(x) = x2-x-6

Set the denominator to zero to find the excluded values:

⇒ x2x6=0x^2-x-6 = 0

Factor the quadratic equation:

⇒​ x23x+2x6=0x^2 - 3x + 2x - 6 = 0

⇒​ x(x3)+2(x3)=0x(x - 3) + 2(x - 3) = 0

⇒​ (x3)(x+2)=0(x - 3)(x + 2) = 0

Set each factor to zero to find the roots:

⇒​ x3=0    x=3x - 3 = 0 \implies x = 3

⇒​ x+2=0    x=2x + 2 = 0 \implies x = -2

The values of x for which the function is undefined are x = -2 and x = 3.

Domain: R2,3\mathbb{R} - {-2, 3}

Option 1 is correct

83

A relation R is defined from NN as R=(a,b):ab,aN and bN.N \to N \text{ as } R = {(a, b) : a \geq b, a \in N \text{ and } b \in N}.. Then R is:

  1. ((a))

    an equivalence relation.

  2. ((b))

    reflecxive and symmetric but not transitive.

  3. ((c))

    reflecxive, neither symmetric nor transitive.

  4. ((d))

    reflecxive and transitive but not symmetric.

Show Answer
Answer: ((d))

reflecxive and transitive but not symmetric.

Calculation:

Given relation: use R=(a,b):ab,a,bNR = {(a, b) : a \ge b, a, b \in \mathbb{N}}

For any use aNa \in \mathbb{N}, we check if use (a,a)R(a, a) \in R.

The condition use aaa \ge a is always true.

    R\implies Ris Reflexive.

Assume use (a,b)R(a, b) \in R, which means use aba \ge b.

For R to be symmetric, we must have use (b,a)R(b, a) \in R, which means  bab \ge a.

If  aba \ge b and use bab \ge a, the only possibility is  a=ba = b.

Consider a counter example: Let a=2 and b=1.

(2,1)R(2, 1) \in R since use 212 \ge 1.

However, (1,2)R(1, 2) \notin R since use 1≱21 \not\ge 2.

R is not Symmetric.

Assume use (a,b)R(a, b) \in R and  (b,c)R(b, c) \in R.

(a,b)R    ab(a, b) \in R \implies a \ge b

(b,c)R    bc(b, c) \in R \implies b \ge c

Since use aba \ge b and use bcb \ge c, it follows that use aca \ge c (property of inequality).

ac    (a,c)Ra \ge c \implies (a, c) \in R.

R is Transitive.

The relation R is reflexive and transitive but not symmetric. This matches option 4.

84

Two sets A and B contains 4 and 5 elements respectively. Number of one one an and onto mapping from A to B is/are: 

  1. ((a))

    120

  2. ((b))

    24

  3. ((c))

     20

  4. ((d))

    0

Show Answer
Answer: ((d))

0

Calculation:

Given data:

Number of elements in set AA, A=4|A| = 4

Number of elements in set BB, B=5|B| = 5

Check the condition for a bijective mapping f:ABf: A \to B:

A=4|A| = 4

B=5|B| = 5

AB|A| \ne |B| since 454 \ne 5.

\Rightarrow Since the number of elements in the domain AA is not equal to the number of elements in the codomain BB, a one-one and onto mapping from AA to BB is not possible.

∴ The number of one-one and onto mappings from AA to BB is 00.

The  correct answer is 0.

85

Let n(U) = 30,  n(A') = 15 ,n(B) = 5 and n (A ∩ B) = 3, then n (AUB) is:

  1. ((a))

    12

  2. ((b))

    25

  3. ((c))

    17

  4. ((d))

    20

Show Answer
Answer: ((c))

17

Concept:

Set Theory:

  • Universal Set: The complete set of all elements under consideration.
  • Complement of a Set (Aʹ): Elements of the universal set that are not in set A.
  • Union of Sets (A ∪ B): Elements that belong to A or B or both.
  • Intersection of Sets (A ∩ B): Elements common to both A and B.
  • Important formula: n(AB)=n(A)+n(B)n(AB) n(A \cup B)=n(A)+n(B)-n(A\cap B)
  • Relation of complement: n(A)+n(A)=n(U) n(A)+n(A')=n(U)

 

Calculation:

Given,

Total elements in universal set, n(U)=30 n(U)=30

Complement of A, n(A)=15 n(A')=15

Elements in B, n(B)=5 n(B)=5

Intersection, n(AB)=3 n(A\cap B)=3

n(A)+n(A)=n(U) n(A)+n(A')=n(U)

n(A)=3015 n(A)=30-15

n(A)=15 n(A)=15

n(AB)=n(A)+n(B)n(AB) n(A\cup B)=n(A)+n(B)-n(A\cap B)

n(AB)=15+53 n(A\cup B)=15+5-3

17 17

∴ The value of n(AB) n(A\cup B) is 17.

86

In a survey of two 400 students of a school, it was found that 100 like to drink coffee, 150 like to drink tea and 75 like both coffee as well as tea. Find how many students neither likes to drink coffee nor tea ? 

  1. ((a))

    175

  2. ((b))

    150

  3. ((c))

    250

  4. ((d))

     225

Show Answer
Answer: ((d))

 225

Calculation:

Given data:

Total number of students (Universal Set), U=400|U| = 400

Number of students who like coffee, C=100|C| = 100

Number of students who like tea, T=150|T| = 150

Number of students who like both coffee and tea, CT=75|C \cap T| = 75

Number of students who like coffee or tea or both (CT|C \cup T|) using the Principle of Inclusion-Exclusion:

CT=C+TCT|C \cup T| = |C| + |T| - |C \cap T|

\Rightarrow CT=100+15075|C \cup T| = 100 + 150 - 75

\Rightarrow CT=25075|C \cup T| = 250 - 75

\Rightarrow CT=175|C \cup T| = 175

The number of students who neither like coffee nor tea (CTc|C \cup T|^c):

CTc=UCT|C \cup T|^c = |U| - |C \cup T|

\Rightarrow CTc=400175|C \cup T|^c = 400 - 175

\Rightarrow CTc=225|C \cup T|^c = 225

∴ The number of students who neither likes to drink coffee nor tea is 225.

87

A ladder makes an angle of 60° with the ground when placed against a wall. If the foot of the ladder is 2m away from the wall, the length of the ladder is: 

  1. ((a))

    434\sqrt{3}  m

  2. ((b))

    43\frac{4}{\sqrt{3}} m

  3. ((c))

    222\sqrt{2} m

  4. ((d))

    4 m

Show Answer
Answer: ((d))

4 m

Calculation:

Given data:

Angle the ladder makes with the ground, θ=60\theta = 60^\circ

Distance of the foot of the ladder from the wall (Base), Base=2 m\text{Base} = 2 \text{ m}

Let the length of the ladder (Hypotenuse) be LL.

Using the cosine trigonometric ratio:

cos(θ)=BaseL\cos(\theta) = \frac{\text{Base}}{L}

\Rightarrow cos(60)=2L\cos(60^\circ) = \frac{2}{L}

\Rightarrow 12=2L\frac{1}{2} = \frac{2}{L}

\Rightarrow L×1=2×2L \times 1 = 2 \times 2

\Rightarrow L=4 mL = 4 \text{ m}

∴ The length of the ladder is 4 m.

88

Solution of the trigonometric equation5cos2x+7sin2x6=0 5cos^2 x + 7sin^2 x - 6 = 0  is:

  1. ((a))

    nπ+π4n \pi + \frac{\pi}{4}

  2. ((b))

    nππ4n \pi - \frac{\pi}{4}

  3. ((c))

    π4\frac{\pi}{4}

  4. ((d))

    nπ±π4n \pi \pm \frac{\pi}{4}

Show Answer
Answer: ((d))

nπ±π4n \pi \pm \frac{\pi}{4}

Calculation:

Given the trigonometric equation:

5cos2x+7sin2x6=05\cos^2x + 7\sin^2x - 6 = 0

Use the identity cos2x=1sin2x\cos^2x = 1 - \sin^2x to express the equation only in terms of sin2x\sin^2x:

\Rightarrow 5(1sin2x)+7sin2x6=05(1 - \sin^2x) + 7\sin^2x - 6 = 0

\Rightarrow 55sin2x+7sin2x6=05 - 5\sin^2x + 7\sin^2x - 6 = 0

\Rightarrow (7sin2x5sin2x)+(56)=0(7\sin^2x - 5\sin^2x) + (5 - 6) = 0

\Rightarrow 2sin2x1=02\sin^2x - 1 = 0

\Rightarrow 2sin2x=12\sin^2x = 1

\Rightarrow sin2x=12\sin^2x = \frac{1}{2}

\Rightarrow 2sin2x=12\sin^2x = 1

\Rightarrow 2(1cos2x)=12(1-\cos^2x) = 1

\Rightarrow 22cos2x=12 - 2\cos^2x = 1

\Rightarrow 2cos2x=12\cos^2x = 1

\Rightarrow cos2x=12\cos^2x = \frac{1}{2}

Since sin2x=12\sin^2x = \frac{1}{2} and cos2x=12\cos^2x = \frac{1}{2}, we have:

\Rightarrow tan2x=sin2xcos2x=1/21/2=1\tan^2x = \frac{\sin^2x}{\cos^2x} = \frac{1/2}{1/2} = 1

We know that tan(π4)=1\tan(\frac{\pi}{4}) = 1, so tan2(π4)=12=1\tan^2(\frac{\pi}{4}) = 1^2 = 1.

\Rightarrow tan2x=tan2(π4)\tan^2x = \tan^2(\frac{\pi}{4})

The general solution for tan2x=tan2α\tan^2x = \tan^2\alpha is x=nπ±αx = n\pi \pm \alpha.

\Rightarrow x=nπ±π4x = n\pi \pm \frac{\pi}{4}, where nZn \in \mathbb{Z}.

∴ The solution of the trigonometric equation is nπ±π4n\pi \pm \frac{\pi}{4}.

89

The minimum value of 25cosx+4sinx+72\sqrt{5} cos x + 4sin x + 7 is:

  1. ((a))

    -2

  2. ((b))

    -1

  3. ((c))

    1

  4. ((d))

    2

Show Answer
Answer: ((c))

1

Calculation:

Given expression is f(x)=25cosx+4sinx+7f(x) = 2\sqrt{5}\cos x + 4\sin x + 7.

This is in the form acosx+bsinx+ca\cos x + b\sin x + c.

a=25a = 2\sqrt{5}

b=4b = 4

c=7c = 7

Amplitude, R=a2+b2R = \sqrt{a^2 + b^2}:

R=(25)2+(4)2R = \sqrt{(2\sqrt{5})^2 + (4)^2}

\Rightarrow R=(4×5)+16R = \sqrt{(4 \times 5) + 16}

\Rightarrow R=20+16R = \sqrt{20 + 16}

\Rightarrow R=36R = \sqrt{36}

\Rightarrow R=6R = 6

The minimum value of the expression f(x)f(x) is f(x)min=cRf(x)_{\text{min}} = c - R:

f(x)min=76f(x)_{\text{min}} = 7 - 6

\Rightarrow f(x)min=1f(x)_{\text{min}} = 1

∴ The minimum value of 25cosx+4sinx+72\sqrt{5}\cos x + 4\sin x + 7 is 1.

90

If a complex number z satisfies the condition i+ziz=1\left|\frac{i+z}{i-z}\right|=1 , then it will lie on :

  1. ((a))

    x - axis

  2. ((b))

    y - axis

  3. ((c))

    circle x2+y2=1

  4. ((d))

    line x+y=1

Show Answer
Answer: ((a))

x - axis

Calculation:

Given the condition for the complex number zz:

i+ziz=1\left|\frac{i + z}{i - z}\right| = 1

Using the modulus property z1z2=z1z2\left|\frac{z_1}{z_2}\right| = \frac{|z_1|}{|z_2|}:

\Rightarrow i+ziz=1\frac{|i + z|}{|i - z|} = 1

\Rightarrow i+z=iz|i + z| = |i - z|

let z=x+iyz = x + iy:

\Rightarrow i+(x+iy)=i(x+iy)|i + (x + iy)| = |i - (x + iy)|

\Rightarrow x+i(1+y)=x+i(1y)|x + i(1 + y)| = |-x + i(1 - y)|

Square the moduli:

\Rightarrow x2+(1+y)2=(x)2+(1y)2x^2 + (1 + y)^2 = (-x)^2 + (1 - y)^2

\Rightarrow x2+1+2y+y2=x2+12y+y2x^2 + 1 + 2y + y^2 = x^2 + 1 - 2y + y^2

Cancel common terms x2x^2, y2y^2, and 11 from both sides:

\Rightarrow 2y=2y2y = -2y

\Rightarrow 4y=04y = 0

\Rightarrow y=0y = 0

The complex number z=x+iyz = x + iy lies on the line where the imaginary part yy is zero. This line is the x-axis in the Argand plane.

∴ The complex number zz will lie on the x-axis.

91

The multiplicative inverse of 3 + 2i is:

  1. ((a))

    313+213i\quad -\frac{3}{13} + \frac{2}{13} i

  2. ((b))

    313+213i\quad \frac{3}{13} + \frac{2}{13} i

  3. ((c))

    313213i\quad \frac{3}{13} - \frac{2}{13} i

  4. ((d))

    313213i\quad -\frac{3}{13} - \frac{2}{13} i

Show Answer
Answer: ((c))

313213i\quad \frac{3}{13} - \frac{2}{13} i

Calculation:

Given the complex number, z=3+2iz = 3 + 2i

Here, the real part is x=3x = 3 and the imaginary part is y=2y = 2.

The multiplicative inverse is z1=1zz^{-1} = \frac{1}{z}.

z1=13+2iz^{-1} = \frac{1}{3 + 2i}

Multiply the numerator and denominator by the conjugate of the denominator, 32i3 - 2i:

\Rightarrow z1=1(3+2i)×(32i)(32i)z^{-1} = \frac{1}{(3 + 2i)} \times \frac{(3 - 2i)}{(3 - 2i)}

\Rightarrow z1=32i(3)2+(2)2z^{-1} = \frac{3 - 2i}{(3)^2 + (2)^2}

\Rightarrow z1=32i9+4z^{-1} = \frac{3 - 2i}{9 + 4}

\Rightarrow z1=32i13z^{-1} = \frac{3 - 2i}{13}

Separate into real and imaginary parts:

\Rightarrow z1=313213iz^{-1} = \frac{3}{13} - \frac{2}{13}i

∴ The multiplicative inverse of 3+2i3 + 2i is 313213i\frac{3}{13} - \frac{2}{13}i.

92

The real value of 0 for which the expression 3+2isinθ12isinθ\frac{3+2 i \sin \theta}{1-2 i \sin \theta} is a real number is:

  1. ((a))

    nππ2n\pi - \frac{\pi}{2}

  2. ((b))

    2nπ2n\pi

  3. ((c))

    nπ+π2n\pi + \frac{\pi}{2}

  4. ((d))

    nπn\pi

Show Answer
Answer: ((d))

nπn\pi

Calculation:

Given the expression z=3+2isinθ12isinθz = \frac{3 + 2i\sin\theta}{1 - 2i\sin\theta}.

To make the denominator real, multiply by the conjugate, 1+2isinθ1 + 2i\sin\theta:

z=3+2isinθ12isinθ×1+2isinθ1+2isinθz = \frac{3 + 2i\sin\theta}{1 - 2i\sin\theta} \times \frac{1 + 2i\sin\theta}{1 + 2i\sin\theta}

\Rightarrow z=(3+2isinθ)(1+2isinθ)(1)2(2isinθ)2z = \frac{(3 + 2i\sin\theta)(1 + 2i\sin\theta)}{(1)^2 - (2i\sin\theta)^2}

\Rightarrow z=3(1)+3(2isinθ)+(2isinθ)(1)+(2isinθ)21(4i2sin2θ)z = \frac{3(1) + 3(2i\sin\theta) + (2i\sin\theta)(1) + (2i\sin\theta)^2}{1 - (4i^2\sin^2\theta)}

Since i2=1i^2 = -1:

\Rightarrow z=3+6isinθ+2isinθ+4(1)sin2θ14(1)sin2θz = \frac{3 + 6i\sin\theta + 2i\sin\theta + 4(-1)\sin^2\theta}{1 - 4(-1)\sin^2\theta}

\Rightarrow z=34sin2θ+i(8sinθ)1+4sin2θz = \frac{3 - 4\sin^2\theta + i(8\sin\theta)}{1 + 4\sin^2\theta}

Split into real and imaginary parts:

\Rightarrow z=34sin2θ1+4sin2θ+i8sinθ1+4sin2θz = \frac{3 - 4\sin^2\theta}{1 + 4\sin^2\theta} + i \frac{8\sin\theta}{1 + 4\sin^2\theta}

For zz to be a real number, the imaginary part must be zero:

\Rightarrow Im(z)=8sinθ1+4sin2θ=0\text{Im}(z) = \frac{8\sin\theta}{1 + 4\sin^2\theta} = 0

Since the denominator 1+4sin2θ1 + 4\sin^2\theta is always positive (non-zero), the numerator must be zero:

\Rightarrow 8sinθ=08\sin\theta = 0

\Rightarrow sinθ=0\sin\theta = 0

The general solution for sinθ=0\sin\theta = 0 is:

\Rightarrow θ=nπ\theta = n\pi, where nZn \in \mathbb{Z}.

∴ The real value of θ\theta for which the expression is a real number is nπn\pi.

93

If sin(sin114+cos1x)=1\sin \left(\sin^{-1} \frac{1}{4} + \cos^{-1} x\right) = 1   then the value of x is :

  1. ((a))

    12\frac{1}{2}

  2. ((b))

    π2\frac{\pi}{2}

  3. ((c))

    14\frac{1}{4}

  4. ((d))

    π4\frac{\pi}{4}

Show Answer
Answer: ((c))

14\frac{1}{4}

Calculation:

Given the equation:

sin(sin114+cos1x)=1\sin \left(\sin^{-1}\frac{1}{4} + \cos^{-1}x \right) = 1

Since sinθ=1\sin\theta = 1 implies θ=π2\theta = \frac{\pi}{2}, we have:

\Rightarrow sin114+cos1x=sin1(1)\sin^{-1}\frac{1}{4} + \cos^{-1}x = \sin^{-1}(1)

\Rightarrow sin114+cos1x=π2\sin^{-1}\frac{1}{4} + \cos^{-1}x = \frac{\pi}{2}

Use the inverse trigonometric property sin1A+cos1A=π2\sin^{-1}A + \cos^{-1}A = \frac{\pi}{2}.

Comparing the expression with the property, the term xx must be equal to 14\frac{1}{4} to satisfy the equation:

\Rightarrow sin114+cos1x=sin114+cos114=π2\sin^{-1}\frac{1}{4} + \cos^{-1}x = \sin^{-1}\frac{1}{4} + \cos^{-1}\frac{1}{4} = \frac{\pi}{2}

For the identity to hold true:

\Rightarrow x=14x = \frac{1}{4}

94

If tan1x+tan1y=2π5\tan^{-1}x + \tan^{-1}y = \frac{2\pi}{5}​, then cot1x+cot1y\cot^{-1}x + \cot^{-1}y is:

  1. ((a))

    π5\frac{\pi}{5}

  2. ((b))

    2π5\frac{2\pi}{5}

  3. ((c))

    3π5\frac{3\pi}{5}

  4. ((d))

    π\pi

Show Answer
Answer: ((c))

3π5\frac{3\pi}{5}

Calculation:

Given data:

The sum of inverse tangents is: tan1x+tan1y=2π5\tan^{-1}x + \tan^{-1}y = \frac{2\pi}{5}

We need to find the value of the expression E=cot1x+cot1yE = \cot^{-1}x + \cot^{-1}y.

Use the identity cot1A=π2tan1A\cot^{-1}A = \frac{\pi}{2} - \tan^{-1}A:

Substitute this identity for both cot1x\cot^{-1}x and cot1y\cot^{-1}y:

E=(π2tan1x)+(π2tan1y)E = \left(\frac{\pi}{2} - \tan^{-1}x\right) + \left(\frac{\pi}{2} - \tan^{-1}y\right)

Group the constant terms and the inverse tangent terms:

\Rightarrow E=(π2+π2)(tan1x+tan1y)E = \left(\frac{\pi}{2} + \frac{\pi}{2}\right) - \left(\tan^{-1}x + \tan^{-1}y\right)

Simplify the sum of π2\frac{\pi}{2}:

\Rightarrow E=π(tan1x+tan1y)E = \pi - \left(\tan^{-1}x + \tan^{-1}y\right)

Substitute the given value tan1x+tan1y=2π5\tan^{-1}x + \tan^{-1}y = \frac{2\pi}{5}:

\Rightarrow E=π2π5E = \pi - \frac{2\pi}{5}

Combine the fractions:

\Rightarrow E=5π52π5E = \frac{5\pi}{5} - \frac{2\pi}{5}

\Rightarrow E=3π5E = \frac{3\pi}{5}

95

If the system of linear equations:

x + y + kz = 4

x - 2y + 2z = 3

3x + y - z = 5

are inconsistent, then the value of k is:

  1. ((a))

    -1

  2. ((b))

    1

  3. ((c))

    0

  4. ((d))

    2

Show Answer
Answer: ((a))

-1

Calculation:

Given the system of linear equations:

x+y+kz=4x + y + kz = 4

x2y+2z=3x - 2y + 2z = 3

3x+yz=53x + y - z = 5

The coefficient matrix AA is:

A=(11k 122 311)A = \begin{pmatrix} 1 & 1 & k \ 1 & -2 & 2 \ 3 & 1 & -1 \end{pmatrix}

For the system to be inconsistent, the determinant must be zero: A=0|A| = 0

Calculate the determinant of AA:

A=1((2)(1)(2)(1))1((1)(1)(2)(3))+k((1)(1)(2)(3))|A| = 1((-2)(-1) - (2)(1)) - 1((1)(-1) - (2)(3)) + k((1)(1) - (-2)(3))

\Rightarrow A=1(22)1(16)+k(1(6))|A| = 1(2 - 2) - 1(-1 - 6) + k(1 - (-6))

\Rightarrow A=1(0)1(7)+k(1+6)|A| = 1(0) - 1(-7) + k(1 + 6)

\Rightarrow A=0+7+7k|A| = 0 + 7 + 7k

\Rightarrow A=7+7k|A| = 7 + 7k

Set the determinant to zero for the possibility of inconsistency:

\Rightarrow 7+7k=07 + 7k = 0

\Rightarrow 7k=77k = -7

\Rightarrow k=1k = -1

∴ The value of kk for which the system is inconsistent is -1.

96

The value of determinant 525354 535455 545556\begin{vmatrix} 5^2 & 5^3 & 5^4 \ 5^3 & 5^4 & 5^5 \ 5^4 & 5^5 & 5^6 \end{vmatrix}

  1. ((a))

    52

  2. ((b))

    0

  3. ((c))

    513

  4. ((d))

    59

Show Answer
Answer: ((b))

0

Calculation:

Given the determinant Δ\Delta:

Δ=525354 535455 545556\Delta = \begin{vmatrix} 5^2 & 5^3 & 5^4 \ 5^3 & 5^4 & 5^5 \ 5^4 & 5^5 & 5^6 \end{vmatrix}

Take out the common factor 525^2 from the first row (R1)(R_1):

\Rightarrow Δ=5215152 535455 545556\Delta = 5^2 \begin{vmatrix} 1 & 5^1 & 5^2 \ 5^3 & 5^4 & 5^5 \ 5^4 & 5^5 & 5^6 \end{vmatrix}

Take out the common factor 535^3 from the second row (R2)(R_2):

\Rightarrow Δ=52×5315152 15152 545556\Delta = 5^2 \times 5^3 \begin{vmatrix} 1 & 5^1 & 5^2 \ 1 & 5^1 & 5^2 \ 5^4 & 5^5 & 5^6 \end{vmatrix}

Observe the rows R1R_1 and R2R_2:

\Rightarrow Since the first row (R1R_1) and the second row (R2R_2) are identical after factorization, the value of the determinant is zero.

\Rightarrow Δ=55×0\Delta = 5^5 \times 0

\Rightarrow Δ=0\Delta = 0

∴ The value of the determinant is 0.

97

A matrix A=[αβ γα]A = \begin{bmatrix} \alpha & \beta \ \gamma & -\alpha \end{bmatrix}    is usch that A2=IA^2=I, then :

  1. ((a))

    1+α2+βγ=01+\alpha^2+\beta\gamma=0

  2. ((b))

    1α2+βγ=01-\alpha^2+\beta\gamma=0

  3. ((c))

    1α2βγ=01-\alpha^2-\beta\gamma=0

  4. ((d))

    1+α2βγ=01+\alpha^2-\beta\gamma=0

Show Answer
Answer: ((c))

1α2βγ=01-\alpha^2-\beta\gamma=0

Calculation:

Given matrix AA and condition A2=IA^2 = I:

A=(αβ γα)A = \begin{pmatrix} \alpha & \beta \ \gamma & -\alpha \end{pmatrix}

A2=A×A=(αβ γα)(αβ γα)A^2 = A \times A = \begin{pmatrix} \alpha & \beta \ \gamma & -\alpha \end{pmatrix} \begin{pmatrix} \alpha & \beta \ \gamma & -\alpha \end{pmatrix}

Perform the matrix multiplication:

\Rightarrow A2=((α)(α)+(β)(γ)(α)(β)+(β)(α) (γ)(α)+(α)(γ)(γ)(β)+(α)(α))A^2 = \begin{pmatrix} (\alpha)(\alpha) + (\beta)(\gamma) & (\alpha)(\beta) + (\beta)(-\alpha) \ (\gamma)(\alpha) + (-\alpha)(\gamma) & (\gamma)(\beta) + (-\alpha)(-\alpha) \end{pmatrix}

\Rightarrow A2=(α2+βγαβαβ γααγβγ+α2)A^2 = \begin{pmatrix} \alpha^2 + \beta\gamma & \alpha\beta - \alpha\beta \ \gamma\alpha - \alpha\gamma & \beta\gamma + \alpha^2 \end{pmatrix}

\Rightarrow A2=(α2+βγ0 0α2+βγ)A^2 = \begin{pmatrix} \alpha^2 + \beta\gamma & 0 \ 0 & \alpha^2 + \beta\gamma \end{pmatrix}

Set A2=IA^2 = I:

\Rightarrow (α2+βγ0 0α2+βγ)=(10 01)\begin{pmatrix} \alpha^2 + \beta\gamma & 0 \ 0 & \alpha^2 + \beta\gamma \end{pmatrix} = \begin{pmatrix} 1 & 0 \ 0 & 1 \end{pmatrix}

Equating the diagonal elements:

\Rightarrow α2+βγ=1\alpha^2 + \beta\gamma = 1

Rearrange the terms:

\Rightarrow 1α2βγ=01 - \alpha^2 - \beta\gamma = 0

∴ The condition for A2=IA^2 = I is 1α2βγ=01 - \alpha^2 - \beta\gamma = 0.

98

Which of the following quadratic equations has two distinct real roots ?

  1. ((a))

    2x2+32x+94=0\quad 2x^2 + 3\sqrt{2}x + \frac{9}{4} = 0

  2. ((b))

    x2+x5=0\quad x^2+x-5=0

  3. ((c))

    x2+3x+22=0\quad x^2 + 3x + 2\sqrt{2} = 0

  4. ((d))

    2x25x+1=0\quad 2x^2 - \sqrt{5}x + 1 = 0

Show Answer
Answer: ((b))

x2+x5=0\quad x^2+x-5=0

Calculation:

We need to find the quadratic equation for which D=b24ac>0D = b^2 - 4ac > 0.

1. Equation 1: 2x2+32x+94=02x^2 + 3\sqrt{2}x + \frac{9}{4} = 0

Given: a=2a = 2, b=32b = 3\sqrt{2}, c=94c = \frac{9}{4}

\Rightarrow D=(32)24(2)(94)D = (3\sqrt{2})^2 - 4(2)\left(\frac{9}{4}\right)

\Rightarrow D=(9×2)8×94D = (9 \times 2) - 8 \times \frac{9}{4}

\Rightarrow D=182×9D = 18 - 2 \times 9

\Rightarrow D=1818=0D = 18 - 18 = 0. (Equal real roots)

2. Equation 2: x2+x5=0x^2 + x - 5 = 0

Given: a=1a = 1, b=1b = 1, c=5c = -5

\Rightarrow D=(1)24(1)(5)D = (1)^2 - 4(1)(-5)

\Rightarrow D=1(20)D = 1 - (-20)

\Rightarrow D=1+20=21D = 1 + 20 = 21

\Rightarrow Since D=21>0D = 21 > 0. (Distinct real roots)

3. Equation 3: x2+3x+22=0x^2 + 3x + 2\sqrt{2} = 0

Given: a=1a = 1, b=3b = 3, c=22c = 2\sqrt{2}

\Rightarrow D=(3)24(1)(22)D = (3)^2 - 4(1)(2\sqrt{2})

\Rightarrow D=982D = 9 - 8\sqrt{2}

\Rightarrow Since 21.414\sqrt{2} \approx 1.414, 8211.3128\sqrt{2} \approx 11.312.

\Rightarrow D911.312<0D \approx 9 - 11.312 < 0. (No real roots)

4. Equation 4: 2x25x+1=02x^2 - \sqrt{5}x + 1 = 0

Given: a=2a = 2, b=5b = -\sqrt{5}, c=1c = 1

\Rightarrow D=(5)24(2)(1)D = (-\sqrt{5})^2 - 4(2)(1)

\Rightarrow D=58D = 5 - 8

\Rightarrow D=3<0D = -3 < 0. (No real roots)

Only Equation 2 has D>0D > 0.

∴ The quadratic equation that has two distinct real roots is x2+x5=0x^2 + x - 5 = 0.

99

The equation of the straight line passing through the point (3, 2) and perpendicular to the line y=x will be: 

  1. ((a))

    x + y = 1

  2. ((b))

    x - y = 1

  3. ((c))

    x - y = 5

  4. ((d))

    x + y = 5

Show Answer
Answer: ((d))

x + y = 5

Calculation:

Given data:

The straight line passes through point P(3,2)P(3, 2). Thus, x1=3x_1 = 3, y1=2y_1 = 2.

The line is perpendicular to the line y=xy = x.

The equation is y=1x+0y = 1x + 0. Slope m1=1m_1 = 1.

Slope m2m_2 of the required perpendicular line

\Rightarrow m2=1m1=11=1m_2 = -\frac{1}{m_1} = -\frac{1}{1} = -1.

Use the point-slope form yy1=m2(xx1)y - y_1 = m_2(x - x_1):

\Rightarrow y2=1(x3)y - 2 = -1(x - 3)

Simplify the equation:

\Rightarrow y2=x+3y - 2 = -x + 3

Rearrange into the form Ax+By+C=0Ax + By + C = 0:

\Rightarrow x+y=3+2x + y = 3 + 2

\Rightarrow x+y=5x + y = 5

∴ The equation of the straight line is x+y=5x + y = 5.

100

The point (4, 1) undergoes the following two successive transformations:

(1) Reflection about the line y=x

(ii) Translation through a distance 2 units along the positive x-axis.

Final coordinate of the point will be:

  1. ((a))

    (72,72)(\frac{7}{2},\frac{7}{2})

  2. ((b))

     (3,4)

  3. ((c))

     (4,3)

  4. ((d))

     (1,4)

Show Answer
Answer: ((b))

 (3,4)

Calculation:

Given initial point: P0=(4,1)P_0 = (4, 1).

(i) Reflection about the line y=xy = x:

\Rightarrow The coordinates are swapped: P1=(1,4)P_1 = (1, 4).

(ii) Translation through a distance 2 units along the positive x-axis:

\Rightarrow The x-coordinate is increased by 2, and the y-coordinate remains the same:

\Rightarrow P2=(1+2,4)P_2 = (1 + 2, 4)

\Rightarrow P2=(3,4)P_2 = (3, 4)

∴ The final coordinate of the point will be (3, 4).

101

Equation of the circle with centre on y-axis and passing through the origin and the point (2, 3) is:

  1. ((a))

    3x2+3y213y=03x^2 + 3y^2 - 13y = 0

  2. ((b))

    3x2+3y2+13y=03x^2 + 3y^2 + 13y = 0

  3. ((c))

    6x2+6y213y=0 6x^2 + 6y^2 - 13y = 0 \

  4. ((d))

    6x2+6y2+13y=06x^2 + 6y^2 + 13y = 0

Show Answer
Answer: ((a))

3x2+3y213y=03x^2 + 3y^2 - 13y = 0

Calculation:

Given data:

Centre lies on y-axis: h=0h = 0. Centre C=(0,k)C = (0, k).

Equation of circle: x2+(yk)2=r2x^2 + (y - k)^2 = r^2.

Passes through origin (0,0)(0, 0). Substitute into the equation:

\Rightarrow 02+(0k)2=r20^2 + (0 - k)^2 = r^2

\Rightarrow k2=r2k^2 = r^2. The radius squared is r2=k2r^2 = k^2.

The equation is now: x2+(yk)2=k2x^2 + (y - k)^2 = k^2.

Expand the equation:

\Rightarrow x2+y22ky+k2=k2x^2 + y^2 - 2ky + k^2 = k^2

\Rightarrow x2+y22ky=0x^2 + y^2 - 2ky = 0

The circle also passes through point (2,3)(2, 3). Substitute x=2x = 2, y=3y = 3:

\Rightarrow 22+322k(3)=02^2 + 3^2 - 2k(3) = 0

\Rightarrow 4+96k=04 + 9 - 6k = 0

\Rightarrow 136k=013 - 6k = 0

Solve for kk:

\Rightarrow 6k=136k = 13

\Rightarrow k=136k = \frac{13}{6}

Substitute k=136k = \frac{13}{6} back into the simplified equation x2+y22ky=0x^2 + y^2 - 2ky = 0:

\Rightarrow x2+y22(136)y=0x^2 + y^2 - 2\left(\frac{13}{6}\right)y = 0

\Rightarrow x2+y2133y=0x^2 + y^2 - \frac{13}{3}y = 0

Multiply the entire equation by 3 to clear the denominator:

\Rightarrow 3x2+3y213y=03x^2 + 3y^2 - 13y = 0

∴ The equation of the circle is 3x2+3y213y=03x^2 + 3y^2 - 13y = 0.

102

If |x - 2| > 6 then: 

  1. ((a))

     χε (-4,8)

  2. ((b))

    x∈(−∞,−4)∪(8,∞)x∈(−∞,−4)∪(8,∞)x∈(−∞,-4)∪(8,∞)

    𝑥 ∈ ( − ∞ , − 4 ) ∪ ( 8 , ∞ )

  3. ((c))

    x∈(−∞,−4]∪[8,∞)x∈(−∞,−4]∪[8,∞)x∈(−∞,-4]∪[8,∞)

    𝑥 ∈ ( − ∞ , − 4 ] ∪ [ 8 , ∞ )

  4. ((d))

    χε [-4, 8]

Show Answer
Answer: ((b))

x∈(−∞,−4)∪(8,∞)x∈(−∞,−4)∪(8,∞)x∈(−∞,-4)∪(8,∞)

𝑥 ∈ ( − ∞ , − 4 ) ∪ ( 8 , ∞ )

Calculation:

Given the inequality:

x2>6|x - 2| > 6

Apply the rule for X>a|X| > a, where X=x2X = x - 2 and a=6a = 6:

\Rightarrow x2<6x - 2 < -6 OR x2>6x - 2 > 6

Solve the first inequality:

\Rightarrow x<6+2x < -6 + 2

\Rightarrow x<4x < -4

Solve the second inequality:

\Rightarrow x>6+2x > 6 + 2

\Rightarrow x>8x > 8

Combine the solutions using the union symbol \cup and interval notation:

\Rightarrow x(,4)x \in (-\infty, -4) OR x(8,)x \in (8, \infty)

\Rightarrow x(,4)(8,)x \in (-\infty, -4) \cup (8, \infty)

∴ The solution to the inequality is x(,4)(8,)x \in (-\infty, -4) \cup (8, \infty).

103

A solution is to be kept between 50° C and 55° C. What is the range of temperature in degree fahrenheit, if the conversion formula is F = 9/5 * C + 32 ?

  1. ((a))

    Between 122°F and 131°F

  2. ((b))

    Between 120°F and 131°F

  3. ((c))

    Between 124°F and 140°F

  4. ((d))

    Between 122°F and 135°F

Show Answer
Answer: ((a))

Between 122°F and 131°F

Calculation:

Given the Celsius temperature range CC:

50C<C<55C50^\circ C < C < 55^\circ C

Given the conversion formula:

F=95×C+32F = \frac{9}{5} \times C + 32

We need to find the lower bound (F1F_1) for C1=50CC_1 = 50^\circ C:

\Rightarrow F1=95×50+32F_1 = \frac{9}{5} \times 50 + 32

\Rightarrow F1=9×10+32F_1 = 9 \times 10 + 32

\Rightarrow F1=90+32F_1 = 90 + 32

\Rightarrow F1=122FF_1 = 122^\circ F

We need to find the upper bound (F2F_2) for C2=55CC_2 = 55^\circ C:

\Rightarrow F2=95×55+32F_2 = \frac{9}{5} \times 55 + 32

\Rightarrow F2=9×11+32F_2 = 9 \times 11 + 32

\Rightarrow F2=99+32F_2 = 99 + 32

\Rightarrow F2=131FF_2 = 131^\circ F

The range in degrees Fahrenheit is between the two calculated values:

\Rightarrow 122F<F<131F122^\circ F < F < 131^\circ F

∴ The range of temperature in degree Fahrenheit is between 122F122^\circ F and 131F131^\circ F.

104

Three balls are drawn from a bag containing three red, five white and two yellow balls. The number of ways in which this can be done, if at least two are red is:

  1. ((a))

    44

  2. ((b))

    120

  3. ((c))

    21

  4. ((d))

    22

Show Answer
Answer: ((d))

22

Concept:

Combinations:

  • Combination is a method of selecting items where the order does not matter.
  • It is denoted by nCr ^nC_r .
  • Formula: nCr=n!r!(nr)! ^nC_r=\frac{n!}{r!(n-r)!}
  • Here, red, white and yellow balls are distinct groups, and we must count selections with at least two red balls.

 

Calculation:

Given,

Total red balls = 3

Total white balls = 5

Total yellow balls = 2

We draw 3 balls.

Case 1: 2 red and 1 non-red

3C2 ^3C_2 for red

7C1 ^7C_1 for (white + yellow)

3C2×7C1 ^3C_2\times ^7C_1

3×7=21 3\times 7=21

Case 2: 3 red

3C3=1 ^3C_3=1

⇒ Total ways = 21+1=22 21+1=22

∴ The number of ways = 22.

105

The number of ways in which a team of 11 players can be selected from 20 players always including one of them and excluding three of them is :

  1. ((a))

    19C10{}^{19}\text{C}_{10}

  2. ((b))

    16C11 {}^{16}\text{C}_{11} \

  3. ((c))

    16C10 {}^{16}\text{C}_{10} \

  4. ((d))

    20C10{}^{20}\text{C}_{10}

Show Answer
Answer: ((c))

16C10 {}^{16}\text{C}_{10} \

Concept:

Combination (selection without order):

  • Selection where order does not matter.
  • Denoted by nCr ^nC_r .
  • Formula: nCr=n!r!(nr)! ^nC_r=\frac{n!}{r!(n-r)!} .
  • Here, important words: always including and excluding.
  • Interpretation: remove excluded players, then force-include the specified player, and choose the rest from remaining pool.

 

Calculation:

Given,

Total players = 20

Excluded players = 3

One player must be included = 1 (fixed)

Team size = 11

⇒ After excluding 3, available players = 20 − 3 = 17

⇒ One specific player is to be included, so remaining spots = 11 − 1 = 10

⇒ Excluding the fixed included player from pool leaves

⇒ remaining candidates = 17 − 1 = 16

⇒ Number of ways = 16C10^{16}C_{10}

∴ The number of ways = 16C10^{16}C_{10}.

106

The number of different four digit numbers that can be formed with the digits 3, 4, 6 and 8 and using each digit only once is :

  1. ((a))

    24

  2. ((b))

    100

  3. ((c))

    80

  4. ((d))

    96

Show Answer
Answer: ((a))

24

Concept:

Permutations:

  • Permutation represents the number of possible arrangements of given distinct objects.
  • When all digits are different, the number of four-digit numbers formed equals the number of ways to arrange the digits.
  • Important formula: nPr=n!(nr)! nPr=\frac{n!}{(n-r)!}
  • For four digits arranged without repetition, total arrangements = 4! 4!

 

Calculation:

Given,

Total digits = 4

Each digit used once only

Total numbers=4! \text{Total numbers}=4!

4!=4×3×2×1 4! =4×3×2×1

24 24

∴ The number of different four-digit numbers is 24.

107

If matrix A=[1100 0110 0010 0002]A = \begin{bmatrix} 1 & 1 & 0 & 0 \ 0 & 1 & 1 & 0 \ 0 & 0 & 1 & 0 \ 0 & 0 & 0 & 2 \end{bmatrix}

then Rank of the matrix (A-I) is:

  1. ((a))

    4

  2. ((b))

    2

  3. ((c))

    3

  4. ((d))

    1

Show Answer
Answer: ((c))

3

Concept:

Rank of a Matrix:

  • Rank of a matrix is the number of non-zero independent rows (or columns).
  • To find the rank, matrices are simplified using elementary row operations.
  • Identity Matrix (I): A square matrix with 1 on the main diagonal and 0 elsewhere.
  • For any matrix A, the matrix (A − I) is obtained by subtracting 1 from each diagonal element.
  • Rank is determined from the number of non-zero rows in the row echelon form.

 

Calculation:

Given,

Matrix \( A=\begin{bmatrix}1&1&0&0\0&1&1&0\0&0&1&0\0&0&0&2\end{bmatrix} \)

Identity matrix \( I=\begin{bmatrix}1&0&0&0\0&1&0&0\0&0&1&0\0&0&0&1\end{bmatrix} \)

 

\( A-I=\begin{bmatrix}1-1&1&0&0\0&1-1&1&0\0&0&1-1&0\0&0&0&2-1\end{bmatrix} \)

\( A-I=\begin{bmatrix}0&1&0&0\0&0&1&0\0&0&0&0\0&0&0&1\end{bmatrix} \)

⇒ Non-zero rows = 3 rows

∴ Rank of (A − I) is 3.

108

If matrix A=[255 031 013].A = \begin{bmatrix} 2 & -5 & 5 \ 0 & 3 & -1 \ 0 & -1 & 3 \end{bmatrix}., then eigen value of the matrix A is:

  1. ((a))

    {2}

  2. ((b))

    {1,4}

  3. ((c))

    (2, 4}

  4. ((d))

    {1, 2}

Show Answer
Answer: ((c))

(2, 4}

Concept:

Eigenvalues of a Matrix:

  • Eigenvalue of a matrix A is a scalar λ such that Av=λv A\vec{v}=\lambda\vec{v} for a non-zero vector v.
  • To find eigenvalues, we use the characteristic equation: AλI=0 |A-\lambda I|=0
  • This gives a polynomial in λ whose roots are eigenvalues.
  • Triangular matrices have eigenvalues equal to their diagonal elements.

 

Calculation:

Given,

\( A=\begin{bmatrix}2&-5&5\0&3&-1\0&-1&3\end{bmatrix} \)

Matrix A is upper triangular except for the last 2×2 block. Eigenvalues are obtained from diagonal entries of triangular blocks.

The lower-right 2×2 block is:

\( \begin{bmatrix}3&-1\-1&3\end{bmatrix} \)

Eigenvalues of this block:

\( \begin{bmatrix}3-\lambda&-1\-1&3-\lambda\end{bmatrix} =0\)

(3λ)21=0 (3-\lambda)^2-1=0

(3λ1)(3λ+1)=0 (3-\lambda-1)(3-\lambda+1)=0

(2λ)(4λ)=0 (2-\lambda)(4-\lambda)=0

λ=2,;4 \lambda=2,;4

∴ Eigenvalues of A are {2, 4}.

109

The characteristic polynomial of matrix A=[111 111 111]A = \begin{bmatrix} 1 & -1 & 1 \ -1 & 1 & -1 \ 1 & -1 & 1 \end{bmatrix}is:

  1. ((a))

    λ3+2λ2-\lambda^3 + 2\lambda^2

  2. ((b))

    λ33λ2 \lambda^3 - 3\lambda^2 \

  3. ((c))

    λ33λ2+4λ \lambda^3 - 3\lambda^2 + 4\lambda \

  4. ((d))

    λ3+3λ2\lambda^3 + 3\lambda^2

Show Answer
Answer: ((b))

λ33λ2 \lambda^3 - 3\lambda^2 \

Concept:

Characteristic Polynomial and Eigenvalues:

  • The characteristic polynomial of an n×n matrix A is det(λIA)\det(\lambda I - A).
  • Eigenvalues are roots of this polynomial. If matrix has rank 1 and trace 3, eigenvalues are 3, 0, 0.

 

Calculation:

Matrix:

\(A=\begin{pmatrix}1 & -1 & 1\[2pt]-1 & 1 & -1\[2pt]1 & -1 & 1\end{pmatrix}\)

Note rows: row1 = row3 and row2 = -row1 ⇒ rank = 1.

Trace = 1+1+1 = 3 ⇒ sum of eigenvalues = 3.

With rank 1, non zero eigenvalue equals trace ⇒ eigenvalues are 3, 0, 0.

Characteristic polynomial (monic):

(λ3)λ2=λ33λ2(\lambda-3)\lambda^2 = \lambda^3-3\lambda^2

Characteristic polynomial = λ33λ2\lambda^3-3\lambda^2

110

If fixi=3100,fi(xixˉ)2=10050\sum f_i x_i = 3100, \sum f_i (x_i - \bar{x})^2 = 10050 and n = 50 then the variance is:

  1. ((a))

    62

  2. ((b))

    101

  3. ((c))

    175

  4. ((d))

    201

Show Answer
Answer: ((d))

201

Concept:

  • Mean (average): The weighted mean x¯x¯

is given by xˉ=fixin\bar{x}=\dfrac{\sum f_i x_i}{n}.

  • Variance: For a population of total frequency n, the variance is the mean of squared deviations: σ2=fi(xixˉ)2n\sigma^2=\dfrac{\sum f_i (x_i-\bar{x})^2}{n}.
  • Given quantities are the sum of weighted observations and the sum of squared deviations.

 

Calculation:

Given,

Σ fixi = 3100

Σ fi(xi − x̄)2 = 10050

n = 50

Compute mean (first, for completeness):

⇒ xˉ=fixin=310050=62\bar{x}=\dfrac{\sum f_i x_i}{n}=\dfrac{3100}{50}=62

Now variance (population formula):

⇒ σ2=fi(xixˉ)2n\sigma^2=\dfrac{\sum f_i (x_i-\bar{x})^2}{n}

⇒ σ2=1005050=201\sigma^2=\dfrac{10050}{50}=201

∴ The variance is 201.

111

In a class test in mathematics, 7 students obtained 10, 45, 35, 43, 25, 46, 15 marks. The mean deviation from the median is:

  1. ((a))

    12.2

  2. ((b))

    11

  3. ((c))

    12

  4. ((d))

    11.6

Show Answer
Answer: ((c))

12

Concept:

  • Median: The median is the middle value of an ordered data set.
  • Mean Deviation from Median: It is the average of absolute deviations from the median.
  • Formula: MD=xiMn MD = \dfrac{\sum |x_i - M|}{n}

 

Calculation:

Given values: 10, 45, 35, 43, 25, 46, 15

Arrange data:

⇒ 10, 15, 25, 35, 43, 45, 46

Median (middle term):

⇒ M = 35

Compute absolute deviations:

⇒ |10 − 35| = 25

⇒ |15 − 35| = 20

⇒ |25 − 35| = 10

⇒ |35 − 35| = 0

⇒ |43 − 35| = 8

⇒ |45 − 35| = 10

⇒ |46 − 35| = 11

Sum of deviations:

⇒ 25 + 20 + 10 + 0 + 8 + 10 + 11 = 84

Mean deviation:

⇒ MD=847=12 MD = \dfrac{84}{7} = 12

∴ The mean deviation from the median is 12.

112

The sum of two non-zero numbers is 6. The minimum value of sum of their reciprocals is:

  1. ((a))

    23 \frac{-2}{3} \

  2. ((b))

    32 \frac{-3}{2} \

  3. ((c))

    23 \frac{2}{3} \

  4. ((d))

    32\frac{3}{2}

Show Answer
Answer: ((c))

23 \frac{2}{3} \

Concept:

  • Reciprocal: The reciprocal of a number x is 1x \frac{1}{x} .
  • We want to find the minimum value of the expression S=1a+1b S = \frac{1}{a} + \frac{1}{b}  given that the numbers satisfy a+b=6 a + b = 6 .
  • Using algebra, S=a+bab=6ab S = \frac{a+b}{ab} = \frac{6}{ab} .
  • To minimize S, we must maximize the product ab.
  • For a fixed sum, the product ab is maximum when numbers are equal.

 

Calculation:

Given:

a + b = 6

⇒ Maximum ab occurs at a = b = 3

⇒ ab = 3 × 3 = 9

⇒ S = 6 / 9

⇒ S=23 S = \frac{2}{3}

∴ The minimum value of the sum of reciprocals is 23 \frac{2}{3} .

113

The equation of tangent to the curve y=x+sin x.cos x at is: x=π2x=\frac{\pi}{2}

  1. ((a))

    y=πy = \pi

  2. ((b))

    y+π=0 y + \pi = 0 \

  3. ((c))

    2y=π 2y = \pi \

  4. ((d))

    y = 2

Show Answer
Answer: ((c))

2y=π 2y = \pi \

Concept:

Tangent to a Curve:

  • The tangent to a curve at a point gives the instantaneous rate of change of the function at that point.
  • The slope of the tangent is obtained by differentiating the given function.
  • Equation of tangent at point (x₀, y₀) with slope m is yy0=m(xx0)y - y_0 = m(x - x_0).
  • For the curve y=x+sinxcosxy = x + \sin x \cos x, differentiation uses product rule.
  • Important: sinxcosx=12sin2x\sin x \cos x = \frac{1}{2}\sin 2x

 

Calculation:

Given,

x₀ = π2\frac{\pi}{2}

y = x + sin x cos x

⇒ sin x cos x = (1/2) sin 2x

⇒ y = x + (1/2) sin 2x

⇒ dy/dx = 1 + cos 2x

⇒ At x = π/2, cos π = −1

⇒ dy/dx = 1 − 1 = 0

⇒ Slope m = 0

⇒ y₀ = π/2 + 0 = π/2

⇒ Tangent: y − π/2 = 0(x − π/2)

∴ 2y = π

114

the diameter of a circle is increasing at the rate of 1cms.1 \frac{\text{cm}}{\text{s}}. When its radius is ㅠ, the rate of increase of its areas (in cm2s)\left(\text{in } \frac{\text{cm}^2}{\text{s}}\right) is

  1. ((a))

    π2 \pi^2 \

  2. ((b))

    2π2 2\pi^2 \

  3. ((c))

    π \pi \

  4. ((d))

    2π2\pi

Show Answer
Answer: ((a))

π2 \pi^2 \

Calculation:

Given radius: r=π r = \pi

The area of a circle is given by A=πr2 A = \pi r^2 .

The diameter D D  is related to radius by D=2r D = 2r .

Given: dDdt=1 cm/s \dfrac{dD}{dt} = 1 \text{ cm/s} . So, drdt=12 cm/s \dfrac{dr}{dt} = \dfrac{1}{2} \text{ cm/s} .

Differentiate area: dAdt=2πr×drdt \dfrac{dA}{dt} = 2\pi r \times \dfrac{dr}{dt} .

Substitute values:

dAdt=2π(π)×12\frac{dA}{dt} = 2\pi(\pi) \times \frac{1}{2}

dAdt=π2 \frac{dA}{dt} =\pi^2

Hence option 1 is correct

115

The approximate value of (33)1/5(33)^{1/5} is:

  1. ((a))

    2.02

  2. ((b))

     2.015

  3. ((c))

    2.15

  4. ((d))

    2.0125

Show Answer
Answer: ((d))

2.0125

Concept:

Approximation using Binomial Expansion:

  • This method is used to approximate expressions of the form (a+h)n (a + h)^n  when h is very small.
  • Approximation formula: (a+h)nan+na,n1h (a + h)^n \approx a^n + n a^{,n-1} h
  • For roots, we write a+hm=(a+h)1/m \sqrt[m]{a+h} = (a+h)^{1/m}  and apply the same approximation.
  • Since 32=25 32 = 2^5 , numbers near 32 can be approximated easily for fifth roots.

 

Calculation:

Given,

Find (33)1/5 (33)^{1/5}

33=32+1 33 = 32 + 1

(32)1/5=2 (32)^{1/5} = 2

Using approximation formula:

(a+h)1/5a1/5+15a4/5h (a+h)^{1/5} \approx a^{1/5} + \frac{1}{5} a^{-4/5} h

a4/5=1324/5 a^{-4/5} = \frac{1}{32^{4/5}}

324/5=(25)4/5=24=16 32^{4/5} = (2^5)^{4/5} = 2^4 = 16

a4/5=116 a^{-4/5} = \frac{1}{16}

(33)1/52+15×116 (33)^{1/5} \approx 2 + \frac{1}{5} \times \frac{1}{16}

15×116=180=0.0125 \frac{1}{5} \times \frac{1}{16} = \frac{1}{80} = 0.0125

∴ (33)1/52.0125 (33)^{1/5} \approx 2.0125

116

23n1,n2^{3n}-1, n \in \text{N }is divisible by:

  1. ((a))

    8

  2. ((b))

    7

  3. ((c))

    9

  4. ((d))

    6

Show Answer
Answer: ((b))

7

Concept:

Modular arithmetic & factorization:

For integer aa, an1a^n-1 is divisible by a1a-1.

Calculation:

23n1=8n12^{3n}-1=8^n-1

⇒ Since an1a^n-1 divisible by a1a-1, take a=8a=8

⇒ Divisor is 81=78-1=7

23n1,n2^{3n}-1, n \in \text{N }is divisible by 7

117

Seema has two coins which appear identical in her purse. She knows that one is fair and other is two headed. She taken out one, toss it and gets a head. The probability that coin was fair is :

  1. ((a))

    13 \frac{1}{3} \

  2. ((b))

    14 \frac{1}{4} \

  3. ((c))

    23 \frac{2}{3} \

  4. ((d))

    34\frac{3}{4}

Show Answer
Answer: ((a))

13 \frac{1}{3} \

Calculation:

Let F = event that chosen coin is fair

Let H = event that result is head

Given,

P(F) = 1/2

P(H|F) = 1/2

P(H|T) = 1

P(T) = 1/2

⇒ P(H) = P(F)×P(H|F) + P(T)×P(H|T)

⇒ P(H) = (1/2)×(1/2) + (1/2)×1

⇒ P(H) = 1/4 + 1/2 = 3/4

⇒ P(F|H) = [P(F)×P(H|F)] / P(H)

⇒ P(F|H) = (1/2 × 1/2) / (3/4)

⇒ P(F|H) = (1/4) ÷ (3/4)

⇒ P(F|H) = 1/3

∴ Probability that the selected coin was fair = 1/3

118

If the probability that a person is not a swimmer is 0.3, then the probability that out of 5 persons, 4 are swimmer is :

  1. ((a))

    5C1(.7)(.3)4 {}^5\text{C}_1 (.7) (.3)^4 \

  2. ((b))

    5C4(.3)4(.7) {}^5\text{C}_4 (.3)^4 (.7) \

  3. ((c))

    (.7)4(.3) (.7)^4 (.3) \

  4. ((d))

    5C4(.7)4(.3){}^5\text{C}_4 (.7)^4 (.3)

Show Answer
Answer: ((d))

5C4(.7)4(.3){}^5\text{C}_4 (.7)^4 (.3)

Concept:

Binomial Distribution:

  • Binomial distribution is used when an experiment has two outcomes: success and failure.
  • The probability of getting exactly k successes in n independent trials is found using the binomial formula.
  • Formula: P(k)=nCk,pk,(1p)nkP(k)=^{n}C_{k},p^{k},(1-p)^{n-k}
  • Here, Success = person is a swimmer.
  • Given probability that a person is not a swimmer = 0.3 ⇒ probability of swimmer = 0.7.
  • Combination nCr^{n}C_{r} gives the number of ways to choose r outcomes from n trials.

 

Calculation:

Let p = probability of swimmer = 0.7

Let q = probability of non-swimmer = 0.3

Let n = 5 persons

Let k = 4 swimmers

P(4)=5C4,p4,qP(4)=^{5}C_{4},p^{4},q

P(4)=5C4,(0.7)4,(0.3)P(4)=^{5}C_{4},(0.7)^{4},(0.3)

∴ Required probability = 5C4(0.7)4(0.3)^{5}C_{4}(0.7)^{4}(0.3)

119

A and B are two events such that P(A) = 0.25 and P(B) = 0.5 The probability of both happening together is 0.14. The probability that both A and B are not happening is:

  1. ((a))

    .61

  2. ((b))

    .75

  3. ((c))

    .39

  4. ((d))

     .86

Show Answer
Answer: ((c))

.39

Calculation:

Given,

P(A)=0.25P(A)=0.25

P(B)=0.50P(B)=0.50

P(AB)=0.14P(A \cap B)=0.14

P(AB)=P(A)+P(B)P(AB)P(A \cup B)=P(A)+P(B)-P(A \cap B)

P(AB)=0.25+0.500.14P(A \cup B)=0.25+0.50-0.14

P(AB)=0.61P(A \cup B)=0.61

P(AB)=1P(AB)P(A' \cap B')=1-P(A \cup B)

P(AB)=10.61P(A' \cap B')=1-0.61

P(AB)=0.39P(A' \cap B')=0.39

∴ The probability that both A and B are not happening is 0.39.

120

The value of tan1(cosx1sinx)\tan^{-1} \left(\frac{\cos x}{1 - \sin x}\right) is.

  1. ((a))

    x2\frac{x}{2}

  2. ((b))

    π4x2\frac{\pi}{4} - \frac{x}{2}

  3. ((c))

    π4+x2 \frac{\pi}{4} + \frac{x}{2} \

  4. ((d))

    π4±x2\frac{\pi}{4} \pm \frac{x}{2}

Show Answer
Answer: ((c))

π4+x2 \frac{\pi}{4} + \frac{x}{2} \

Concept:

Trigonometric transformation and inverse tangent:

  • Goal: simplify the expression inside the inverse tangent to a single tangent of an angle.
  • Key identity used: multiply numerator and denominator by the conjugate to use 1sin2x=cos2x1-\sin^2 x=\cos^2 x.
  • Half-angle substitution: let t=tanx2t=\tan\frac{x}{2}, and use sinx=2t1+t2, cosx=1t21+t2\sin x=\dfrac{2t}{1+t^2},\ \cos x=\dfrac{1-t^2}{1+t^2}.
  • Tangent addition formula: tan(A+B)=tanA+tanB1tanAtanB\tan(A+B)=\dfrac{\tan A+\tan B}{1-\tan A\tan B}.

 

Calculation:

Given expression inside arctan,

T=cosx1sinxT=\dfrac{\cos x}{1-\sin x}

First simplification

Multiply numerator and denominator by 1+sinx1+\sin x:

T=cosx(1+sinx)(1sinx)(1+sinx)T=\dfrac{\cos x(1+\sin x)}{(1-\sin x)(1+\sin x)}

T=cosx(1+sinx)1sin2xT=\dfrac{\cos x(1+\sin x)}{1-\sin^2 x}

T=cosx(1+sinx)cos2xT=\dfrac{\cos x(1+\sin x)}{\cos^2 x}

T=1+sinxcosxT=\dfrac{1+\sin x}{\cos x}

Use half-angle substitution t=tanx2t=\tan\frac{x}{2}:

sinx=2t1+t2, cosx=1t21+t2\sin x=\dfrac{2t}{1+t^2},\ \cos x=\dfrac{1-t^2}{1+t^2}

T=1+2t1+t21t21+t2=1+t2+2t1t2T=\dfrac{1+\dfrac{2t}{1+t^2}}{\dfrac{1-t^2}{1+t^2}}=\dfrac{1+t^2+2t}{1-t^2}

T=(1+t)2(1t)(1+t)=1+t1tT=\dfrac{(1+t)^2}{(1-t)(1+t)}=\dfrac{1+t}{1-t}

T=1+tanx21tanx2=tan(π4+x2)T=\dfrac{1+\tan\frac{x}{2}}{1-\tan\frac{x}{2}}=\tan\Big(\dfrac{\pi}{4}+\dfrac{x}{2}\Big)

Therefore the original inverse tangent equals

tan1!(cosx1sinx)=π4+x2\tan^{-1}!\left(\dfrac{\cos x}{1-\sin x}\right)=\dfrac{\pi}{4}+\dfrac{x}{2}

tan1!(cosx1sinx)=π4+x2.\tan^{-1}!\left(\dfrac{\cos x}{1-\sin x}\right)=\dfrac{\pi}{4}+\dfrac{x}{2}.

121

If a\vec{a}, b\vec{b} and c\vec{c} are unit vectors such that a+b+c=0\vec{a} + \vec{b} + \vec{c} = \vec{0}, then the value of ab+bc+ca\vec{a} \cdot \vec{b} + \vec{b} \cdot \vec{c} + \vec{c} \cdot \vec{a}is:

  1. ((a))

    1

  2. ((b))

    32 \frac{3}{2} \

  3. ((c))

    32-\frac{3}{2}

  4. ((d))

    0

Show Answer
Answer: ((c))

32-\frac{3}{2}

Concept:

Vector identity and dot product:

  • If a+b+c=0 \vec a+\vec b+\vec c=\vec 0  then their resultant is the zero vector.
  • Use the identity v2=vv |\vec v|^2=\vec v\cdot\vec v .
  • Expand a+b+c2 |\vec a+\vec b+\vec c|^2  to relate the dot products.
  • Given unit vectors: a=b=c=1 |\vec a|=|\vec b|=|\vec c|=1 .

Calculation:

Given,

a+b+c=0 \vec a+\vec b+\vec c=\vec 0

Let

S=ab+bc+ca S=\vec a\cdot\vec b+\vec b\cdot\vec c+\vec c\cdot\vec a

Square the zero vector:

a+b+c2=0 |\vec a+\vec b+\vec c|^2=0

=aa+bb+cc+2(ab+bc+ca) =\vec a\cdot\vec a+\vec b\cdot\vec b+\vec c\cdot\vec c+2(\vec a\cdot\vec b+\vec b\cdot\vec c+\vec c\cdot\vec a)

Since unit vectors:

a2=b2=c2=1 |\vec a|^2=|\vec b|^2=|\vec c|^2=1

3+2S=0 3+2S=0

2S=3 2S=-3

S=32 S=-\dfrac{3}{2}

∴ The value is 32 -\dfrac{3}{2} .

122

The position vector of the point which divides the join of points 4a+b and a2b4 \vec{a} + \vec{b} \text{ and } \vec{a} - 2 \vec{b} externally in the ratio 2:3 is:

  1. ((a))

    15(14ab) \frac{1}{5} \left(14 \vec{a} - \vec{b}\right) \

  2. ((b))

    15(11a4b) \frac{1}{5} \left(11 \vec{a} - 4\vec{b}\right) \

  3. ((c))

    5a+8b 5 \vec{a} + 8\vec{b} \

  4. ((d))

    10a+7b10 \vec{a} + 7\vec{b}

Show Answer
Answer: ((d))

10a+7b10 \vec{a} + 7\vec{b}

Concept:

Section formula (vectors):

  • If a point divides the join of position vectors r1 \mathbf{r_1} and r2 \mathbf{r_2} externally in the ratio m:n m:n .
  • Formula for external division: r=mr2nr1mn \displaystyle \mathbf{r}=\frac{m\mathbf{r_2}-n\mathbf{r_1}}{m-n}

Calculation:

Given,

r1=4a+b \mathbf{r_1}=4\mathbf{a}+\mathbf{b}

r2=a2b \mathbf{r_2}=\mathbf{a}-2\mathbf{b}

Ratio: m:n=2:3 m:n = 2:3

r=mr2nr1mn \mathbf{r}=\frac{m\mathbf{r_2}-n\mathbf{r_1}}{m-n}

r=2(a2b)3(4a+b)23 \mathbf{r}=\frac{2(\mathbf{a}-2\mathbf{b})-3(4\mathbf{a}+\mathbf{b})}{2-3}

r=2a4b12a3b1 \mathbf{r}=\frac{2\mathbf{a}-4\mathbf{b}-12\mathbf{a}-3\mathbf{b}}{-1}

r=10a7b1 \mathbf{r}=\frac{-10\mathbf{a}-7\mathbf{b}}{-1}

r=10a+7b \mathbf{r}=10\mathbf{a}+7\mathbf{b}

123

The projection of AB=i^2j^+4k^ on CD=i^+2j^+2k^\overrightarrow{\text{AB}} = \hat{i} - 2\hat{j} + 4\hat{k} \text{ on } \overrightarrow{\text{CD}} = -\hat{i} + 2\hat{j} + 2\hat{k} is:

  1. ((a))

    143 \frac{14}{3} \

  2. ((b))

    1

  3. ((c))

    4

  4. ((d))

    53\frac{5}{3}

Show Answer
Answer: ((b))

1

Calculation:

Given vectors

AB=i^2j^+4k^ \vec{AB}=\hat{i}-2\hat{j}+4\hat{k}

CD=i^+2j^+2k^ \vec{CD}=-\hat{i}+2\hat{j}+2\hat{k}

Compute dot product

ABCD=1×(1)+(2)×2+4×2 \vec{AB}\cdot\vec{CD} =1\times(-1)+(-2)\times2+4\times2

ABCD=14+8=3 \vec{AB}\cdot\vec{CD}=-1-4+8=3

Compute norm of CD \vec{CD}

CD=(1)2+22+22=9=3 |\vec{CD}| =\sqrt{(-1)^2+2^2+2^2}=\sqrt{9}=3

Scalar projection (component) of AB \vec{AB} on CD \vec{CD}:

ABCDCD=33=1 \dfrac{\vec{AB}\cdot\vec{CD}}{|\vec{CD}|} =\dfrac{3}{3}=1

∴ The projection of AB \vec{AB} on CD \vec{CD} is 11.

124

The value of i^×(j^+k^)+j^×(k^+i^)+k^×(i^+j^)\hat{i} \times (\hat{j} + \hat{k}) + \hat{j} \times (\hat{k} + \hat{i}) + \hat{k} \times (\hat{i} + \hat{j}) is equal to :

  1. ((a))

    2(i^+j^+k^) 2(\hat{i} + \hat{j} + \hat{k}) \

  2. ((b))

    0

  3. ((c))

    1

  4. ((d))

    i^+j^+k^\hat{i} + \hat{j} + \hat{k}

Show Answer
Answer: ((b))

0

Concept:

  • The cross product is anti-commutative: u×v=,v×u \mathbf{u} \times \mathbf{v} = -,\mathbf{v} \times \mathbf{u} .
  • Standard basis cross products: i^×j^=k^ \hat{i} \times \hat{j} = \hat{k} , j^×k^=i^ \hat{j} \times \hat{k} = \hat{i} , k^×i^=j^ \hat{k} \times \hat{i} = \hat{j} .
  • Linearity of cross product: a×(b+c)=a×b+a×c \mathbf{a} \times (\mathbf{b} + \mathbf{c}) = \mathbf{a} \times \mathbf{b} + \mathbf{a} \times \mathbf{c} .

Solution:

Given expression:

i^×(j^+k^)+j^×(k^+i^)+k^×(i^+j^) \hat{i} \times (\hat{j} + \hat{k}) + \hat{j} \times (\hat{k} + \hat{i}) + \hat{k} \times (\hat{i} + \hat{j})

=i^×j^+i^×k^+j^×k^+j^×i^+k^×i^+k^×j^ = \hat{i}\times\hat{j} + \hat{i}\times\hat{k} + \hat{j}\times\hat{k} + \hat{j}\times\hat{i} + \hat{k}\times\hat{i} + \hat{k}\times\hat{j}

=k^j^+i^k^+j^i^ = \hat{k} - \hat{j} + \hat{i} - \hat{k} + \hat{j} - \hat{i}

⇒ (i^i^)+(j^j^)+(k^k^)=0 (\hat{i}-\hat{i}) + (\hat{j}-\hat{j}) + (\hat{k}-\hat{k}) = \mathbf{0}

∴ Final Answer: 0 \mathbf{0}

125

If the rth term in the expansion of (2x21x)12\left(2x^2 - \frac{1}{x}\right)^{12}is without x, then r is:

  1. ((a))

    7

  2. ((b))

    8

  3. ((c))

    9

  4. ((d))

    10

Show Answer
Answer: ((c))

9

Concept:

Binomial Theorem:

  • The binomial expansion of (a+b)n (a+b)^n contains terms of the form Tr+1=(nr)a,nrb,r T_{r+1}=\binom{n}{r}a^{,n-r}b^{,r} .
  • To find a term without x, we set the power of x equal to zero

Calculation:

Given,

(2x21x)12 (2x^2-\frac{1}{x})^{12}

General term,

Tr+1=(12r)(2x2)12r(1x)r T_{r+1}=\binom{12}{r}(2x^2)^{12-r}\left(-\frac{1}{x}\right)^r

⇒ power of x = 2(12r)r 2(12-r)-r

242rr 24-2r-r

243r 24-3r

For term without x:

243r=0 24-3r=0

3r=24 3r=24

r=8 r=8

∴ The r**th term in the expansion is 9**

126

If the coefficients of(r1)th,rth and (r+1)th(r-1)^{\text{th}}, r^{\text{th}} \text{ and } (r+1)^{\text{th}} terms in the expansion of (x+1)n(x+1)^n are in the ratio 1:3:5, then value of n is:

  1. ((a))

    8

  2. ((b))

    4

  3. ((c))

    3

  4. ((d))

    7

Show Answer
Answer: ((d))

7

Concept:

Binomial Theorem:

  • The general term in the expansion of (x+1)n (x+1)^n is Tr+1=(nr)x,r T_{r+1}=\binom{n}{r}x^{,r} .
  • The coefficient of the (r1)th (r-1)^{\text{th}} term is (nr2) \binom{n}{r-2} .
  • The coefficient of the rth r^{\text{th}} term is (nr1) \binom{n}{r-1} .
  • The coefficient of the (r+1)th (r+1)^{\text{th}} term is (nr) \binom{n}{r} .

Calculation:

Given,

Coefficient ratio: (nr2):(nr1):(nr)=1:3:5 \binom{n}{r-2} : \binom{n}{r-1} : \binom{n}{r} = 1:3:5

Consider first ratio:

(nr2)(nr1)=13 \frac{\binom{n}{r-2}}{\binom{n}{r-1}} = \frac{1}{3}

(r1)(nr+2)=13 \frac{(r-1)}{(n-r+2)} = \frac{1}{3}

3(r1)=nr+2 3(r-1)=n-r+2

3r3=nr+2 3r-3=n-r+2

4r=n+5 4r=n+5

Second ratio:

(nr1)(nr)=35 \frac{\binom{n}{r-1}}{\binom{n}{r}} = \frac{3}{5}

r(nr+1)=35 \frac{r}{(n-r+1)} = \frac{3}{5}

5r=3(nr+1) 5r=3(n-r+1)

5r=3n3r+3 5r=3n-3r+3

8r=3n+3 8r=3n+3

Now solve both:

⇒ From 4r=n+5 4r=n+5 n=4r5 n=4r-5

Substitute:

8r=3(4r5)+3 8r=3(4r-5)+3

8r=12r15+3 8r=12r-15+3

8r=12r12 8r=12r-12

4r=12 4r=12

r=3 r=3

n=4r5 n=4r-5 = 125=7 12-5=7

∴ The value of n is 7.

127

The coefficients of xnx^n in the expansion of (1+x)2n and (1+x)2n1(1+x)^{2n} \text{ and } (1+x)^{2n-1}are in the ratio:

  1. ((a))

    1:2

  2. ((b))

    2:1

  3. ((c))

    3:1

  4. ((d))

    1:3

Show Answer
Answer: ((b))

2:1

Concept:

Binomial Theorem:

  • The general term in (1+x)m (1+x)^m is Tk+1=(mk)x,k T_{k+1}=\binom{m}{k}x^{,k} .
  • The coefficient of xn x^n in (1+x)2n (1+x)^{2n} is (2nn) \binom{2n}{n} .
  • The coefficient of xn x^n in (1+x)2n1 (1+x)^{2n-1} is (2n1n) \binom{2n-1}{n} .

 

Calculation:

Given, coefficients ratio:

(2nn):(2n1n) \binom{2n}{n} : \binom{2n-1}{n}

(2nn)(2n1n) \frac{\binom{2n}{n}}{\binom{2n-1}{n}}

(2n)!n!n!÷(2n1)!n!(n1)! \frac{(2n)!}{n!n!} \div \frac{(2n-1)!}{n!(n-1)!}

(2n)!(2n1)!×(n1)!n! \frac{(2n)!}{(2n-1)!} \times \frac{(n-1)!}{n!}

(2n)×1n (2n) \times \frac{1}{n}

2 2

∴ The ratio is 2 : 1.

128

The first and last terms of an AP are 1 and 11. If the sum of the terms is 48, then the number of terms are:

  1. ((a))

    9

  2. ((b))

    7

  3. ((c))

    8

  4. ((d))

    6

Show Answer
Answer: ((c))

8

Concept:

Arithmetic Progression:

  • An Arithmetic Progression (AP) is a sequence of numbers where the difference between consecutive terms is constant.
  • The sum of n terms of an AP is given by Sn=n2(a+l) S_n=\frac{n}{2}(a+l) , where a = first term, l = last term.
  • This formula is used when the first and last terms are known.

 

Calculation:

Given,

First term, a = 1

Last term, l = 11

Sum, S = 48

Using formula S=n2(a+l) S=\frac{n}{2}(a+l)

48=n2(1+11) 48=\frac{n}{2}(1+11)

48=n2×12 48=\frac{n}{2}\times 12

48=6n 48=6n

n=8 n=8

∴ The number of terms is 8.

129

If second term of a G.P. is 2 and the sum of its infinite terms is 8, then the first term is:

  1. ((a))

    14 \frac{1}{4} \

  2. ((b))

    2

  3. ((c))

    12\frac{1}{2}

  4. ((d))

    4

Show Answer
Answer: ((d))

4

Concept:

Geometric Progression:

  • A Geometric Progression (G.P.) is a sequence in which each term is obtained by multiplying the previous term by a constant ratio.
  • The nᵗʰ term of a G.P. is ar,n1 a r^{,n-1} , where a = first term, r = common ratio.
  • The sum of infinite terms of a G.P. (for |r| < 1) is S=a1r S_\infty=\frac{a}{1-r} .

 

Calculation:

Given,

Second term = 2

Sum of infinite terms = 8

Second term = ar=2 ar=2

Sum formula: a1r=8 \frac{a}{1-r}=8

a=8(1r) a=8(1-r)

⇒ Substitute in ar=2 ar=2

8(1r)r=2 8(1-r)r=2

8r8r2=2 8r-8r^2=2

4r4r2=1 4r-4r^2=1

4r24r+1=0 4r^2-4r+1=0

(2r1)2=0 (2r-1)^2=0

r=12 r=\frac{1}{2}

Now, ar=2a=2r=21/2=4 ar=2 \Rightarrow a=\frac{2}{r}=\frac{2}{1/2}=4

∴ The first term is 4.

130

Let SnS_ndenote the sum of first n elements of and an AP. If S2n=3Sn, then S3n:SnS_{2n}=3 S_n, \text{ then } S_{3n} : S_nis equal to:

  1. ((a))

    4

  2. ((b))

    6

  3. ((c))

    8

  4. ((d))

    10

Show Answer
Answer: ((b))

6

Concept:

  • The sum of first n n terms of an AP is Sn=n2(2a+(n1)d) S_n = \frac{n}{2}\left(2a + (n-1)d\right) .
  • We use the relation S2n=3Sn S_{2n} = 3S_n .
  • We must find the ratio S3n:Sn S_{3n} : S_n .

Calculation:

Sn=n2(2a+(n1)d) S_n = \frac{n}{2}\left(2a + (n-1)d\right)

S2n=2n2(2a+(2n1)d)=n(2a+(2n1)d) S_{2n} = \frac{2n}{2}\left(2a + (2n-1)d\right) = n\left(2a + (2n-1)d\right)

Given:

S2n=3Sn S_{2n} = 3S_n

Substitute expressions:

n(2a+(2n1)d)=3[n2(2a+(n1)d)] n\left(2a + (2n-1)d\right) = 3 \left[\frac{n}{2}\left(2a + (n-1)d\right)\right]

Divide both sides by n n :

2a+(2n1)d=32(2a+(n1)d) 2a + (2n-1)d = \frac{3}{2}\left(2a + (n-1)d\right)

Solve:

4a+2(2n1)d=3(2a+(n1)d) 4a + 2(2n-1)d = 3(2a + (n-1)d)

4a+(4n2)d=6a+3(n1)d 4a + (4n-2)d = 6a + 3(n-1)d

4a+(4n2)d=6a+(3n3)d 4a + (4n-2)d = 6a + (3n-3)d

Rearranging:

(4n23n+3)d=2a (4n-2 - 3n + 3)d = 2a

(n+1)d=2a (n+1)d = 2a

So, a=(n+1)d2 a = \frac{(n+1)d}{2} .

S3n=3n2(2a+(3n1)d) S_{3n} = \frac{3n}{2}\left(2a + (3n-1)d\right)

Substitute a=(n+1)d2 a = \frac{(n+1)d}{2} :

2a=(n+1)d 2a = (n+1)d

S3n=3n2((n+1)d+(3n1)d) S_{3n} = \frac{3n}{2}\left((n+1)d + (3n-1)d\right)

=3n2((4n)d) = \frac{3n}{2} \left((4n)d\right)

=6n2d = 6n^2 d

Sn=n2(2a+(n1)d) S_n = \frac{n}{2}\left(2a + (n-1)d\right)

Again substitute a=(n+1)d2 a = \frac{(n+1)d}{2} :

2a=(n+1)d 2a = (n+1)d

Sn=n2((n+1)d+(n1)d) S_n = \frac{n}{2}\left((n+1)d + (n-1)d\right)

=n2(2nd) = \frac{n}{2} (2n d)

=n2d = n^2 d

S3nSn=6n2dn2d=6 \frac{S_{3n}}{S_n} = \frac{6n^2 d}{n^2 d} = 6

131

If a, 4, b are in AP and a, 2, b are in GP, then a, 1, b are in:

  1. ((a))

    AP

  2. ((b))

    GP

  3. ((c))

    HP

  4. ((d))

    neither AP nor HP

Show Answer
Answer: ((c))

HP

Concept:

Arithmetic Progression (AP):

  • AP has constant difference between consecutive terms.
  • If a, b, c are in AP, then 2b=a+c2b = a + c.

Geometric Progression (GP):

  • GP has constant ratio between consecutive terms.
  • If a, b, c are in GP, then b2=acb^2 = ac.

Harmonic Progression (HP):

  • Three numbers are in HP if their reciprocals are in AP.
  • This means: a,,1,,b are in HP     11,,1a,,1b are in APa,,1,,b \text{ are in HP } \iff \frac{1}{1},,\frac{1}{a},,\frac{1}{b} \text{ are in AP}

 

Calculation:

Given,

a, 4, b are in AP

a, 2, b are in GP

From AP condition,

4a=b44 - a = b - 4

b=8ab = 8 - a

From GP condition,

22=ab2^2 = ab

4=a(8a)4 = a(8 - a)

4=8aa24 = 8a - a^2

a28a+4=0a^2 - 8a + 4 = 0

a=8±64162a=\frac{8\pm\sqrt{64-16}}{2}

a=8±482a=\frac{8\pm\sqrt{48}}{2}

a=8±432a=\frac{8\pm4\sqrt{3}}{2}

a=4±23a=4\pm2\sqrt{3}

Now,

b=8ab = 8 - a

⇒ For a=4+23a=4+2\sqrt{3}, b=423b=4-2\sqrt{3}

⇒ For a=423a=4-2\sqrt{3}, b=4+23b=4+2\sqrt{3}

Check if a, 1, b form GP:

12ab1^2 \neq ab

⇒ GP fails.

Check HP condition:

11,,1a,,1b\frac{1}{1},,\frac{1}{a},,\frac{1}{b} must be in AP.

2(1a)=1+1b2\left(\frac{1}{a}\right) = 1 + \frac{1}{b}

⇒ This identity holds for both values of a and b.

∴ a, 1, b are in HP.

132

If z1z_1 andz2z_2 are two complex numbers, then which one of the following is not true ?

  1. ((a))

    z1z2=z1z2 |z_1 \cdot z_2| = |z_1| \cdot |z_2| \

  2. ((b))

    z1+z2z1+z2 |z_1 + z_2| \leq |z_1| + |z_2| \

  3. ((c))

    z1z2z1z2 |z_1 - z_2| \leq ||z_1| - |z_2|| \

  4. ((d))

    z1+z22+z1z22=2(z12+z22)|z_1 + z_2|^2 + |z_1 - z_2|^2 = 2(|z_1|^2 + |z_2|^2)

Show Answer
Answer: ((c))

z1z2z1z2 |z_1 - z_2| \leq ||z_1| - |z_2|| \

Concept:

Modulus / Absolute value of a complex number:

  • If z=x+iyz=x+iy then z=x2+y2|z|=\sqrt{x^2+y^2}.
  • Important property (multiplicative): z1z2=z1,z2|z_1z_2|=|z_1|,|z_2|.
  • Triangle inequality: z1+z2z1+z2|z_1+z_2|\le |z_1|+|z_2|.
  • Reverse triangle (difference) inequality: z1z2z1z2 \big||z_1|-|z_2|\big|\le |z_1-z_2| .
  • Parallelogram identity: z1+z22+z1z22=2(z12+z22)|z_1+z_2|^2+|z_1-z_2|^2 = 2(|z_1|^2+|z_2|^2).

 

Calculation:

Given,

z1,z2z1,z2

are complex numbers.

Check each statement:

  1. z1z2=z1,z2|z_1z_2|=|z_1|,|z_2|

⇒ This is a standard property of modulus. It is true.

  1. z1+z2z1+z2|z_1+z_2|\le |z_1|+|z_2|

⇒ This is the triangle inequality. It is true.

  1. z1z2z1z2|z_1-z_2|\le ||z_1|-|z_2||

⇒ The correct inequality is z1z2z1z2||z_1|-|z_2||\le |z_1-z_2|.

⇒ So statement (3) reverses the inequality and is generally false.

⇒ Provide a simple counter example:

⇒ Take z1=1,;z2=1z_1=1,; z_2=-1.

⇒ Then z1z2=1(1)=2|z_1-z_2|=|1-(-1)|=2.

⇒ And z1z2=11=0||z_1|-|z_2||=|1-1|=0.

⇒ So (3) would assert 202\le 0, which is false.

  1. z1+z22+z1z22=2(z12+z22)|z_1+z_2|^2+|z_1-z_2|^2=2(|z_1|^2+|z_2|^2)

⇒ This is the parallelogram identity. It is true.

∴ Option 3 is not true

133

The angle between the two lines and x+22=y17=z+33 and x+21=2y84=z54\frac{-x + 2}{-2} = \frac{y - 1}{7} = \frac{z + 3}{-3} \text{ and } \frac{x + 2}{-1} = \frac{2y - 8}{4} = \frac{z - 5}{4} is

  1. ((a))

    30°

  2. ((b))

    60°

  3. ((c))

     45°

  4. ((d))

    90°

Show Answer
Answer: ((d))

90°

Concept:

Vector form of a line & angle between lines:

  • A line in symmetric form xx0l=yy0m=zz0n \frac{x-x_0}{l}=\frac{y-y_0}{m}=\frac{z-z_0}{n} has direction ratios (l,m,n) (l,m,n) .
  • If two direction vectors are u\mathbf{u} and v\mathbf{v}, the angle θ between them satisfies cosθ=uvuv \cos\theta=\dfrac{\mathbf{u}\cdot\mathbf{v}}{|\mathbf{u}||\mathbf{v}|} .
  • If uv=0\mathbf{u}\cdot\mathbf{v}=0 then the lines are perpendicular and θ=90\theta=90^\circ.

 

Calculation:

Given the two symmetric forms, convert to direction ratios.

Line 1: x+22=y17=z+33 \dfrac{-x+2}{-2}=\dfrac{y-1}{7}=\dfrac{z+3}{-3}

⇒ Put common parameter tt :

x+2=2tx=2+2t-x+2=-2t\Rightarrow x=2+2t

y1=7ty=1+7ty-1=7t\Rightarrow y=1+7t

z+3=3tz=33tz+3=-3t\Rightarrow z=-3-3t

⇒ Direction vector for line 1: v1=(2,;7,;3)\mathbf{v_1}=(2,;7,;-3)

Line 2: x+21=2y84=z54 \dfrac{x+2}{-1}=\dfrac{2y-8}{4}=\dfrac{z-5}{4}

⇒ Put common parameter ss :

x+2=1sx=2sx+2=-1s\Rightarrow x=-2-s

2y8=4sy=4+2s2y-8=4s\Rightarrow y=4+2s

z5=4sz=5+4sz-5=4s\Rightarrow z=5+4s

⇒ Direction vector for line 2: v2=(1,;2,;4)\mathbf{v_2}=(-1,;2,;4)

Compute dot product:

v1v2=2(1)+7(2)+(3)(4)\mathbf{v_1}\cdot\mathbf{v_2} =2(-1)+7(2)+(-3)(4)

=2+1412=0= -2+14-12 = 0

⇒ Since v1v2=0\mathbf{v_1}\cdot\mathbf{v_2}=0,

⇒ The lines are perpendicular.

∴ The angle between the two lines is 9090^\circ.

134

Coordinates of a point/ the points on a line which is/are at a distance x+23=y+12=z32\frac{x + 2}{3} = \frac{y + 1}{2} = \frac{z - 3}{2}

5 units from a point P(1, 3, 3) is / are :

  1. ((a))

     (-2,-1, 3) and (4, 3, 7)

  2. ((b))

    (-2,-1, 3)

  3. ((c))

    (-2,3,-1) and (4, 7, 3)

  4. ((d))

    (4, 7, 3)

Show Answer
Answer: ((a))

 (-2,-1, 3) and (4, 3, 7)

Concept:

  • Distance between two points: The distance between points (x1,y1,z1) (x_1,y_1,z_1) and (x2,y2,z2) (x_2,y_2,z_2) is (x2x1)2+(y2y1)2+(z2z1)2 \sqrt{(x_2-x_1)^2+(y_2-y_1)^2+(z_2-z_1)^2} .
  • Direction ratios of a line: For symmetric form x+23=y+12=z32=t \dfrac{x+2}{3}=\dfrac{y+1}{2}=\dfrac{z-3}{2}=t , direction ratios are (3,2,2) (3,2,2) .
  • Point on line using parameter: Coordinates on the line are obtained by substituting parameter t t .
  • Required condition: Distance of the point from P(1, 3, 3) must be 5 units.

 

Calculation:

Line in parametric form:

x = −2 + 3t

y = −1 + 2t

z = 3 + 2t

Distance from P(1,3,3) is 5:

[(2+3t)1]2+[(1+2t)3]2+[(3+2t)3]2=25 [(−2+3t)-1]^2 + [(-1+2t)-3]^2 + [(3+2t)-3]^2 = 25

(3t3)2+(2t4)2+(2t)2=25 (3t−3)^2 + (2t−4)^2 + (2t)^2 = 25

9t218t+9+4t216t+16+4t2=25 9t^2−18t+9 + 4t^2−16t+16 + 4t^2 = 25

17t234t+25=25 17t^2 −34t +25 = 25

17t234t=0 17t^2 −34t = 0

17t(t2)=0 17t(t−2)=0

t=0 t=0 or t=2 t=2

For t = 0:

⇒ x = −2, y = −1, z = 3

For t = 2:

⇒ x = 4, y = 3, z = 7

∴ Required points are (−2, −1, 3) and (4, 3, 7).

135

The value of λ\lambda for which the vectors a=4i^+6j^+2k^,b=i^4j^3k^\vec{a} = 4\hat{i} + 6\hat{j} + 2\hat{k}, \vec{b} = \hat{i} - 4\hat{j} - 3\hat{k} and c=λi^+j^3k^\vec{c} = \lambda \hat{i} + \hat{j} - 3\hat{k}are coplanar is:

  1. ((a))

    -4

  2. ((b))

    0

  3. ((c))

    8

  4. ((d))

    4

Show Answer
Answer: ((c))

8

Concept:

  • Three vectors are coplanar if their scalar triple product is zero.
  • The scalar triple product (STP) of vectors a,b,c \vec{a}, \vec{b}, \vec{c} is:

\( [\vec{a}\ \vec{b}\ \vec{c}] = \begin{vmatrix} a_1 & b_1 & c_1 \[4pt] a_2 & b_2 & c_2 \[4pt] a_3 & b_3 & c_3 \end{vmatrix} \)

  • If this determinant is zero → vectors are coplanar.

Calculation

a=4i^+6j^+2k^,b=1i^4j^3k^,c=λi^+1j^3k^ \vec{a} = 4\hat{i} + 6\hat{j} + 2\hat{k},\quad \vec{b} = 1\hat{i} - 4\hat{j} - 3\hat{k},\quad \vec{c} = \lambda \hat{i} + 1\hat{j} - 3\hat{k}

41λ 641 233=0 \begin{vmatrix} 4 & 1 & \lambda \ 6 & -4 & 1 \ 2 & -3 & -3 \end{vmatrix} = 0 ( 4 \begin{vmatrix} -4 & 1 \ -3 & -3 \end{vmatrix} - 1 \begin{vmatrix} 6 & 1 \ 2 & -3 \end{vmatrix} + \lambda \begin{vmatrix} 6 & -4 \ 2 & -3 \end{vmatrix} = 0 \)

4[(4)(3)(1)(3)][6(3)(1)(2)]+λ[6(3)(4)(2)]=0 4[(-4)(-3) - (1)(-3)] - [6(-3) - (1)(2)] + \lambda [6(-3) - (-4)(2)] = 0

4[12+3][182]+λ[18+8]=0 4[12 + 3] - [-18 - 2] + \lambda[-18 + 8] = 0

4(15)+2010λ=0 4(15) + 20 - 10\lambda = 0

60+2010λ=0 60 + 20 - 10\lambda = 0

80=10λ 80 = 10\lambda

λ=8 \lambda = 8

136

The centre of a sphere which passes through the points (a, 0, 0), (0, b, 0), (0, 0, c) and (0, 0, 0),

( where a, b.c≠0) is:

  1. ((a))

    (a2,0,0) \left(\frac{a}{2}, 0, 0\right) \

  2. ((b))

    (0,0,c2) \left(0, 0, \frac{c}{2}\right) \

  3. ((c))

    (0,b2,0) \left(0, \frac{b}{2}, 0\right) \

  4. ((d))

    (a2,b2,c2)\left(\frac{a}{2}, \frac{b}{2}, \frac{c}{2}\right)

Show Answer
Answer: ((d))

(a2,b2,c2)\left(\frac{a}{2}, \frac{b}{2}, \frac{c}{2}\right)

Concept:

Sphere:

  • A sphere is the set of all points in 3D space that are at an equal distance (called the radius) from a fixed point called the centre.
  • Centre of a sphere is the point that is equidistant from all points on its surface.
  • The sphere passing through points (a,0,0), (0,b,0), (0,0,c) and the origin (0,0,0) will have its centre on the line joining equal-distance points.

Calculation:

Given points: A(a,0,0)A(a,0,0), B(0,b,0)B(0,b,0), C(0,0,c)C(0,0,c), O(0,0,0)O(0,0,0)

Assume centre = P(x,y,z)P(x,y,z)

Distance OP:

x2+y2+z2x^2+y^2+z^2

Distance AP:

(xa)2+y2+z2(x-a)^2+y^2+z^2

Equating OP and AP:

x2+y2+z2=(xa)2+y2+z2x^2+y^2+z^2=(x-a)^2+y^2+z^2

0=x22ax+a2x20=x^2-2ax+a^2-x^2

2ax=a22ax=a^2

x=a2x=\frac{a}{2}

Similarly, equating OP and BP:

y=b2y=\frac{b}{2}

Similarly, OP = CP:

z=c2z=\frac{c}{2}

∴ The centre of the sphere is (a2,b2,c2)\left(\frac{a}{2},\frac{b}{2},\frac{c}{2}\right).

137

If the function f(x) = (x - 1)(x - 2)(x - 3) satisfy the Lagrange's Mean Value Theorem in the interval [0, 4]. The number of values of C will be:

  1. ((a))

    0

  2. ((b))

    1

  3. ((c))

    2

  4. ((d))

    3

Show Answer
Answer: ((c))

2

Concept:

Mean Value Theorem (Lagrange's MVT):

MVT states: If a function is continuous on [a,b] and differentiable on (a,b), then ∃ c in (a,b) such that f(c)=f(b)f(a)baf'(c)=\dfrac{f(b)-f(a)}{b-a}.

Calculation:

Given function, f(x)=(x1)(x2)(x3)f(x)=(x-1)(x-2)(x-3)

Expand,

f(x)=x36x2+11x6f(x)=x^3-6x^2+11x-6

Differentiate,

f(x)=3x212x+11f'(x)=3x^2-12x+11

f(0)=6,;f(4)=6f(0)=-6,; f(4)=6

Average slope on [0,4],

f(4)f(0)40=6(6)4=3\dfrac{f(4)-f(0)}{4-0}=\dfrac{6-(-6)}{4}=3

Solve MVT equation,

f(x)=3f'(x)=3

3x212x+11=33x^2-12x+11=3

3x212x+8=03x^2-12x+8=0

Quadratic roots,

x=12±144966=12±486=6±233x=\dfrac{12\pm\sqrt{144-96}}{6} =\dfrac{12\pm\sqrt{48}}{6} =\dfrac{6\pm2\sqrt3}{3}

Check interval,

6233(0,4),;6+233(0,4)\dfrac{6-2\sqrt3}{3}\in(0,4),; \dfrac{6+2\sqrt3}{3}\in(0,4)

∴ The number of values of cc is 2.

138

If f(x)=3x and g(x)=x22+4.f(x) = 3x \text{ and } g(x) = \frac{x^2}{2} + 4., then which of the following can be a discontinuous function ?

  1. ((a))

    f(x)+g(x) f(x) + g(x) \

  2. ((b))

    f(x)g(x) f(x) - g(x) \

  3. ((c))

    f(x)g(x) f(x) \cdot g(x) \

  4. ((d))

    g(x)f(x)\frac{g(x)}{f(x)}

Show Answer
Answer: ((d))

g(x)f(x)\frac{g(x)}{f(x)}

Concept:

Continuity of Functions:

  • A function is continuous if it has no breaks, jumps, or undefined points in its domain.
  • If f(x) and g(x) are continuous functions, then:
  • f(x) + g(x) is continuous.
  • f(x) − g(x) is continuous.
  • f(x) × g(x) is continuous.
  • The expression g(x)f(x) \dfrac{g(x)}{f(x)} may become discontinuous if f(x)=0 f(x)=0 for any value in the domain because division by zero is undefined.

 

Calculation:

Given functions:

f(x)=3x f(x)=3x

g(x)=x22+4 g(x)=\dfrac{x^2}{2}+4

Check denominator for discontinuity:

f(x)=0 f(x)=0

3x=0 3x=0

x=0 x=0

Thus, g(x)f(x) \dfrac{g(x)}{f(x)} is undefined at x=0 x=0 .

∴ The function that can be discontinuous is g(x)f(x) \dfrac{g(x)}{f(x)} .

139

If y=sinx+y, then dydxy=\sqrt{\sin x + y}, \text{ then } \frac{dy}{dx} is equal to :

  1. ((a))

    cosx12y \frac{\cos x}{1 - 2y} \

  2. ((b))

    sinx12y \frac{\sin x}{1 - 2y} \

  3. ((c))

    cosx2y1 \frac{\cos x}{2y - 1} \

  4. ((d))

    sinx2y1\frac{\sin x}{2y - 1}

Show Answer
Answer: ((c))

cosx2y1 \frac{\cos x}{2y - 1} \

Concept:

Implicit Differentiation & Chain Rule:

Implicit function: When y is defined in terms of x by an equation that is not explicitly solved for y, we use implicit differentiation to find dy/dxdy/dx.

Chain rule: If y appears inside another function (for example inside a square root), differentiate the outer function and multiply by the derivative of the inner function.

Calculation:

Given, y=sinx+yy=\sqrt{\sin x+y}

Square both sides:

y2=sinx+yy^2=\sin x+y

Differentiate both sides w.r.t. xx:

ddx(y2)=ddx(sinx+y)\dfrac{d}{dx}(y^2)=\dfrac{d}{dx}(\sin x+y)

2y,dydx=cosx+dydx2y,\dfrac{dy}{dx}=\cos x+\dfrac{dy}{dx}

2y,dydxdydx=cosx2y,\dfrac{dy}{dx}-\dfrac{dy}{dx}=\cos x

(2y1)dydx=cosx(2y-1)\dfrac{dy}{dx}=\cos x

dydx=cosx2y1\dfrac{dy}{dx}=\dfrac{\cos x}{2y-1}.

140

limx1(x1)(2x3)2x2+x3\lim_{x \to 1} \frac{(\sqrt{x} - 1) (2x - 3)}{2x^2 + x - 3} is equal to :

  1. ((a))

    110 -\frac{1}{10} \

  2. ((b))

    -2

  3. ((c))

    1

  4. ((d))

    -1

Show Answer
Answer: ((a))

110 -\frac{1}{10} \

Calculation:

Given expression,

L=limx1(x1)(2x3)2x2+x3L=\lim_{x\to1}\frac{(\sqrt{x}-1)(2x-3)}{2x^2+x-3}

First simplify x1\sqrt{x}-1

x1=x1x+1\sqrt{x}-1=\frac{x-1}{\sqrt{x}+1}

L=limx1(x1)(2x3)(x+1)(2x2+x3)L=\lim_{x\to1}\frac{(x-1)(2x-3)}{(\sqrt{x}+1)(2x^2+x-3)}

Factor denominator:

2x2+x3=(x1)(2x+3)2x^2+x-3=(x-1)(2x+3)

L=limx12x3(x+1)(2x+3)L=\lim_{x\to1}\frac{2x-3}{(\sqrt{x}+1)(2x+3)}

Put x = 1:

L=2(1)3(1+1)(2(1)+3)L=\frac{2(1)-3}{(1+1)(2(1)+3)}

L=12×5L=\frac{-1}{2×5}

L=110L=-\frac{1}{10}

∴ The value of the limit is −1/10.

141

Solution of the differential equation dydx+ycotx=4xcosecx,\frac{dy}{dx} + y \cot x = 4x \operatorname{cosec} x,

  1. ((a))

    ysinx=2x2+c y \sin x = 2x^2 + c \

  2. ((b))

    ysinx=x2+c y \sin x = x^2 + c \

  3. ((c))

    ysinx+x2=c y \sin x + x^2 = c \

  4. ((d))

    ysinx+2x2=cy \sin x + 2x^2 = c

Show Answer
Answer: ((a))

ysinx=2x2+c y \sin x = 2x^2 + c \

Concept:

Linear Differential Equation:

  • A first-order differential equation of the form dydx+P(x)y=Q(x) \frac{dy}{dx}+P(x)y=Q(x) is called a linear differential equation.
  • The required integrating factor (I.F.) is IF=eP(x),dx IF=e^{\int P(x),dx} .
  • The complete solution is y(IF)=Q(x)(IF),dx+C y(IF)=\int Q(x)(IF),dx + C .

Calculation:

Given Differential equation:

dydx+ycotx=4x cosecx \frac{dy}{dx}+y\cot x = 4x \ cosecx

Integrating factor,

IF=ecotx,dx IF = e^{\int \cot x,dx}

IF=eln(sinx) IF = e^{\ln(\sin x)}

IF=sinx IF = \sin x

Multiply whole equation by IF:

sinxdydx+ysinxcotx=4x \sin x\frac{dy}{dx}+y\sin x\cot x = 4x

ddx(ysinx)=4x \frac{d}{dx}(y\sin x)=4x

Integrate both sides:

ysinx=4x,dx y\sin x = \int 4x,dx

ysinx=2x2+C y\sin x = 2x^2 + C

Hence, the solution is ysinx=2x2+C y\sin x = 2x^2 + C .

142

The solution of the differential equation (1+x2)dydx+1+y2=0,(1+x^2)\frac{dy}{dx} + 1+y^2 = 0, is

  1. ((a))

    tan1xtan1y=c \tan^{-1} x - \tan^{-1} y = c \

  2. ((b))

    tan1y±tan1x=c \tan^{-1} y \pm \tan^{-1} x = c \

  3. ((c))

    tan1yxtan1x=c \tan^{-1} y - x \tan^{-1} x = c \

  4. ((d))

    tan1x+tan1y=c\tan^{-1} x + \tan^{-1} y = c

Show Answer
Answer: ((d))

tan1x+tan1y=c\tan^{-1} x + \tan^{-1} y = c

Concept:

Differential Equation:

  • A first–order differential equation of the form M(x,y),dx+N(x,y),dy=0 M(x,y),dx + N(x,y),dy = 0 can be solved by separating variables when possible..

Calculation:

Given,

(1+x2)dydx+1+y2=0 (1+x^2)\frac{dy}{dx}+1+y^2=0

(1+x2)dydx=(1+y2) (1+x^2)\frac{dy}{dx}=-(1+y^2)

dy1+y2=dx1+x2 \frac{dy}{1+y^2}=-\frac{dx}{1+x^2}

Integrate both sides,

dy1+y2=dx1+x2 \int\frac{dy}{1+y^2}=\int -\frac{dx}{1+x^2}

tan1y=tan1x+C \tan^{-1}y = - \tan^{-1}x + C

Hence, the solution is tan1y+tan1x=C \tan^{-1}y + \tan^{-1}x = C .

143

A solution of the differential equation  x dy - ydx represents:

  1. ((a))

     a rectangular hyperbola.

  2. ((b))

    parabola whose vertex is at origin.

  3. ((c))

    straight line passing through origin.

  4. ((d))

     A circle whose centre is at the origin.

Show Answer
Answer: ((c))

straight line passing through origin.

Concept:

Differential Equation (Separable):

  • Separable equation — can be written as a function of y times dy equals a function of x times dx.
  • Integrating both sides gives the general solution containing an arbitrary constant.
  • Family of solutions of the form y=Cxy=Cx are straight lines through the origin.

 

Calculation:

Given differential equation:

x,dyy,dx=0x,dy - y,dx = 0

x,dy=y,dxx,dy = y,dx

dyy=dxx\dfrac{dy}{y}=\dfrac{dx}{x}

⇒ Integrate both sides:

dyy=dxx\int \dfrac{dy}{y}=\int \dfrac{dx}{x}

lny=lnx+C\ln|y|=\ln|x|+C

y=eCx|y|=e^{C}|x|

⇒ Let k=eCk=e^{C}, so y=kxy=kx

∴ The general solution is y=Cxy=Cx, a family of straight lines through the origin.

144

Which of the following equation is a homogeneous differential equation?

  1. ((a))

    (x2+xy)dy=(x2+y)dx (x^2 + xy) dy = (x^2 + y) dx \

  2. ((b))

    xcos(yx)dydx=ycos(yx)+x x \cos \left(\frac{y}{x}\right) \frac{dy}{dx} = y \cos \left(\frac{y}{x}\right) + x \

  3. ((c))

    xdydx1+xsin(yx)=0 x \frac{dy}{dx} - 1 + x \sin \left(\frac{y}{x}\right) = 0 \

  4. ((d))

    x2dydx=x2y+xyx^2 \frac{dy}{dx} = x - 2y + xy

Show Answer
Answer: ((b))

xcos(yx)dydx=ycos(yx)+x x \cos \left(\frac{y}{x}\right) \frac{dy}{dx} = y \cos \left(\frac{y}{x}\right) + x \

Concept:

  • A first–order differential equation is homogeneous if it can be written in the form dydx=F(yx) \dfrac{dy}{dx} = F\left(\dfrac{y}{x}\right) .
  • This means the right-hand side should depend only on the ratio y/x y/x , not on x or y separately.
  • To check homogeneity, simplify the differential equation and observe whether it reduces to a function of y/x y/x alone.

 

Calculation

Option 1:

(x2+xy),dy=(x2+y),dx (x^2 + xy),dy = (x^2 + y),dx

dydx=x2+yx2+xy \dfrac{dy}{dx} = \dfrac{x^2 + y}{x^2 + xy} → mixture of degrees → Not homogeneous

Option 2:

xcos(yx)dydx=ycos(yx)+x x\cos\left(\dfrac{y}{x}\right)\dfrac{dy}{dx} = y\cos\left(\dfrac{y}{x}\right) + x

Divide both sides by xcos(yx) x\cos\left(\dfrac{y}{x}\right) :

dydx=yx+1cos(yx) \dfrac{dy}{dx} = \dfrac{y}{x} + \dfrac{1}{\cos\left(\dfrac{y}{x}\right)}

The right-hand side depends only on y/x y/x .

⇒ This is a homogeneous differential equation.

Option 3:

xdydx1+xsin(yx)=0 x\dfrac{dy}{dx} - 1 + x\sin\left(\dfrac{y}{x}\right)=0

dydx=1xsin(yx) \dfrac{dy}{dx} = \dfrac{1}{x} - \sin\left(\dfrac{y}{x}\right)

The term 1/x 1/x depends on x alone → Not homogeneous

Option 4:

x2dydx=x2y+xy x^2 \dfrac{dy}{dx} = x - 2y + xy

dydx=xx22yx2+xyx2 \dfrac{dy}{dx} = \dfrac{x}{x^2} - 2\dfrac{y}{x^2} + \dfrac{xy}{x^2}

Simplifies to mixed-degree terms → Not homogeneous

Option 2 is the homogeneous differential equation.

145

The area of the region (in sq units) bounded by the lines x = 2y + 3, y = 1 and y = - 1 is:

  1. ((a))

    4

  2. ((b))

    6

  3. ((c))

    32\frac{3}{2}

  4. ((d))

    8

Show Answer
Answer: ((b))

6

Concept:

Area of a plane region bounded by vertical / horizontal / straight lines:

​The area is given by Area=ab(f(y)g(y)),dy \text{Area}=\displaystyle\int_{a}^{b} \big(f(y)-g(y)\big),dy .​

Calculation:

Area =   11(2y+3),dy \displaystyle\int_{-1}^{1} (2y+3),dy

[y2+3y]11 \big[y^{2}+3y\big]_{-1}^{1}

(12+31)((1)2+3(1)) (1^{2}+3\cdot1)-((-1)^{2}+3\cdot(-1))

(1+3)(13)=4(2)=6 (1+3)-(1-3)=4-(-2)=6

  ∴ Area = 66 square units.

146

The value of 0π/2ex(sinxcosx)dx\int_{0}^{\pi/2} e^x (\sin x - \cos x) dx is

  1. ((a))

    1

  2. ((b))

    0

  3. ((c))

    π2\frac{\pi}{2}

  4. ((d))

    2

Show Answer
Answer: ((a))

1

Calculation

I=ex(sinxcosx),dx I=\int e^{x}(\sin x-\cos x),dx

We use known integrals:

  • exsinx,dx=ex2(sinxcosx) \displaystyle \int e^{x}\sin x,dx=\frac{e^{x}}{2}(\sin x-\cos x)
  • excosx,dx=ex2(sinx+cosx) \displaystyle \int e^{x}\cos x,dx=\frac{e^{x}}{2}(\sin x+\cos x)

Thus,

I=ex(sinxcosx),dx \displaystyle I=\int e^{x}(\sin x-\cos x),dx

=ex2(sinxcosx)ex2(sinx+cosx) =\frac{e^{x}}{2}(\sin x-\cos x)-\frac{e^{x}}{2}(\sin x+\cos x)

=ex2[2cosx]=excosx =\frac{e^{x}}{2}[-2\cos x] = -e^{x}\cos x

0π/2ex(sinxcosx),dx=[excosx]0π/2 \displaystyle \int_{0}^{\pi/2} e^{x}(\sin x-\cos x),dx = [-e^{x}\cos x]_{0}^{\pi/2}

=eπ/2cos(π/2)+e0cos(0) = -e^{\pi/2}\cos(\pi/2) + e^{0}\cos(0)

= 0+1= 1

147

The value of cos2xcos2θcosxcosθdx\int \frac{\cos 2x - \cos 2\theta}{\cos x - \cos \theta} dx is

  1. ((a))

    sinx2xcosθ+c \sin x - 2x \cos \theta + c \

  2. ((b))

    2(sinxxcosθ)+c 2(\sin x - x \cos \theta) + c \

  3. ((c))

    2(sinx+xcosθ)+c 2(\sin x + x \cos \theta) + c \

  4. ((d))

    2sinx+xcosθ+c2\sin x + x \cos \theta + c

Show Answer
Answer: ((c))

2(sinx+xcosθ)+c 2(\sin x + x \cos \theta) + c \

Calculation

We use the trigonometric identity:

cos2xcos2θ=2(cosx+cosθ)(cosxcosθ) \cos 2x - \cos 2\theta = 2(\cos x + \cos \theta)(\cos x - \cos \theta)

Substitute into the integral:

cos2xcos2θcosxcosθ,dx=2(cosx+cosθ)(cosxcosθ)cosxcosθ,dx \int \frac{\cos 2x - \cos 2\theta}{\cos x - \cos \theta} , dx = \int \frac{2(\cos x + \cos \theta)(\cos x - \cos \theta)}{\cos x - \cos \theta} , dx

Cancel the term cosxcosθ \cos x - \cos \theta :

=2(cosx+cosθ),dx = \int 2(\cos x + \cos \theta) , dx

Integrate term-by-term:

=2cosx,dx+2cosθdx = 2\int \cos x , dx + 2\cos\theta \int dx

=2sinx+2xcosθ+C = 2\sin x + 2x\cos\theta + C

148

The value of  x2(x2+1)(x2+4)dx\int \frac{x^2}{(x^2 + 1) (x^2 + 4)} dx is

  1. ((a))

    13tan1x+23tan1x2+c \frac{1}{3} \tan^{-1} x + \frac{2}{3} \tan^{-1} \frac{x}{2} + c \

  2. ((b))

    13tan1x+23tan1x2+c -\frac{1}{3} \tan^{-1} x + \frac{2}{3} \tan^{-1} \frac{x}{2} + c \

  3. ((c))

    13tan1x+13tan1x2+c \frac{1}{3} \tan^{-1} x + \frac{1}{3} \tan^{-1} \frac{x}{2} + c \

  4. ((d))

    13tan1x+13tan1x2+c-\frac{1}{3} \tan^{-1} x + \frac{1}{3} \tan^{-1} \frac{x}{2} + c

Show Answer
Answer: ((b))

13tan1x+23tan1x2+c -\frac{1}{3} \tan^{-1} x + \frac{2}{3} \tan^{-1} \frac{x}{2} + c \

Concept:

Partial Fraction Decomposition:

  • Used to break a rational function into simpler fractions.
  • Helps integrate expressions of the form x2(x2+1)(x2+4) \frac{x^2}{(x^2+1)(x^2+4)} .
  • Arctan integration formula: dxx2+a2=1atan1(xa) \int \frac{dx}{x^2+a^2}=\frac{1}{a}\tan^{-1}\left(\frac{x}{a}\right) .
  • After decomposition, each term becomes standard for inverse tangent.

 

Calculation:

Given,

x2(x2+1)(x2+4),dx \displaystyle \int \frac{x^2}{(x^2+1)(x^2+4)},dx

x2(x2+1)(x2+4)=Ax2+1+Bx2+4 \frac{x^2}{(x^2+1)(x^2+4)}=\frac{A}{x^2+1}+\frac{B}{x^2+4}

⇒ x2=A(x2+4)+B(x2+1) x^2=A(x^2+4)+B(x^2+1)

x2=(A+B)x2+(4A+B) x^2=(A+B)x^2+(4A+B)

⇒ A+B=1,;;4A+B=0 A+B=1,;;4A+B=0

⇒ A=13,;;B=43 A=-\tfrac13,;;B=\tfrac43

⇒ x2(x2+1)(x2+4)=13(x2+1)+43(x2+4) \frac{x^2}{(x^2+1)(x^2+4)} =-\frac{1}{3(x^2+1)}+\frac{4}{3(x^2+4)}

⇒ 13dxx2+1+43dxx2+4 -\tfrac13\int\frac{dx}{x^2+1} +\tfrac43\int\frac{dx}{x^2+4}

⇒ 13tan1x+43×12tan1(x2) -\tfrac13\tan^{-1}x +\tfrac43\times\tfrac12\tan^{-1}\left(\tfrac x2\right)

⇒ 13tan1x+23tan1(x2)+C -\tfrac13\tan^{-1}x +\tfrac23\tan^{-1}\left(\tfrac x2\right) +C

∴ Hence, the value of the integral is 13tan1x+23tan1(x2)+C -\tfrac13\tan^{-1}x+\tfrac23\tan^{-1}\left(\tfrac x2\right)+C .

149

The circlesx2+y2+6x+2y+8=0 x ^ 2 + y ^ 2 + 6x + 2y + 8 = 0 and x2+y28x4y+4=0:x ^ 2 + y ^ 2 - 8x - 4y + 4 = 0 :

  1. ((a))

    touch internally.

  2. ((b))

     touch externally

  3. ((c))

     intersect each other.

  4. ((d))

     do not intersect.

Show Answer
Answer: ((d))

 do not intersect.

Concept:

Circle (standard form):

  • General form: x2+y2+2gx+2fy+c=0x^2+y^2+2gx+2fy+c=0.
  • Centre: (g,f)(-g,-f); Radius: r=g2+f2cr=\sqrt{g^2+f^2-c}.
  • Distance between centres: d=(x2x1)2+(y2y1)2d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}.
  • Position conditions (for two circles):
  • If d=r1+r2d=r_1+r_2 → touch externally.
  • If d=r2r1d=|r_2-r_1| → touch internally.
  • If r2r1 |r_2-r_1| → intersect.
  • If d>r1+r2d>r_1+r_2 → do not intersect (separate).

 

Calculation:

Given circles,

  1. x2+y2+6x+2y+8=0x^2+y^2+6x+2y+8=0

(x+3)2+(y+1)22=0(x+3)^2+(y+1)^2-2=0

⇒ Centre C1=(3,1)C_1=(-3,-1),

⇒ Radius r1=2r_1=\sqrt{2}

  1. x2+y28x4y+4=0x^2+y^2-8x-4y+4=0

(x4)2+(y2)216=0(x-4)^2+(y-2)^2-16=0

⇒ Centre C2=(4,2)C_2=(4,2),

⇒ Radius r2=4r_2=4

Distance between centres:

d=(4(3))2+(2(1))2=49+9=58.d=\sqrt{(4-(-3))^2+(2-(-1))^2}=\sqrt{49+9}=\sqrt{58}.

r1+r2=2+45.414r_1+r_2=\sqrt{2}+4\approx 5.414

d7.616d\approx 7.616

∴ Hence,d>r1+r2d>r_1+r_2, so the circles do not intersect.

150

A survey shows that 54% of the students from an school like to read short stories where as 62% like to read poems. If x%, of the students like to read both short stories and poems, then :

  1. ((a))

     x = 84

  2. ((b))

     x = 16

  3. ((c))

    16x6216 \leq x \leq 62

  4. ((d))

    16x5416 \leq x \leq 54

Show Answer
Answer: ((d))

16x5416 \leq x \leq 54

Concept:

Set Theory (Intersection of Sets):

  • Percentage: It represents a part per hundred of a quantity.
  • Intersection of Sets: It represents the common part between two sets.
  • If A% students like one activity and B% like another, then the % who like both is given by:

xA+B100x \ge A + B - 100

  • The maximum possible % of students who like both activities is the smaller of the two values:

xmin(A,B)x \le \min(A , B)

 

Calculation:

Given,

Short stories liking % = 54%

Poems liking % = 62%

Minimum value of x,

xmin=54+62100x_{min}=54+62-100

xmin=16x_{min}=16

Maximum value of x,

xmax=min(54,62)x_{max}=\min(54,62)

xmax=54x_{max}=54

∴ The valid range of x is 16x5416 \le x \le 54.

151

If f(x) = sinx + cosx, then the maximum value of f(x) is:

  1. ((a))

    2

  2. ((b))

    2(3)2\sqrt(3)

  3. ((c))

    (2)\sqrt(2)

  4. ((d))

    3(2)3\sqrt(2)

Show Answer
Answer: ((c))

(2)\sqrt(2)

Concept:

Trigonometric Maximum Value:

  • Trigonometric functions such as sinx and cosx have maximum value 1 and minimum value −1.
  • For any expression of the form asinx+bcosxa\sin x + b\cos x, its maximum value is given by:

a2+b2 \sqrt{a^2 + b^2}

  • This result comes from applying the Cauchy–Schwarz inequality or expressing the function as a single sine wave.

Calculation:

Given,

Function: f(x)=sinx+cosxf(x)=\sin x + \cos x

Maximum value formula,

fmax=a2+b2f_{max}=\sqrt{a^2 + b^2}

fmax=12+12f_{max}=\sqrt{1^2 + 1^2}

fmax=2f_{max}=\sqrt{2}

∴ The maximum value of f(x) is 22.

152

If A is a square matrix, then which among the following is/are true ?

(i) A+ A' is a symmetric matrix.

(ii) A-A' is a symmetric matrix.

(iii) AA' is a skew symmetric matrix.

  1. ((a))

    only (i) is true.

  2. ((b))

    only (ii) is true.

  3. ((c))

    only (iii) is true.

  4. ((d))

    (i) and (iii) are true.

Show Answer
Answer: ((a))

only (i) is true.

Concept:

Matrix Symmetry:

  • Square matrix: A matrix having equal number of rows and columns.
  • Transpose of matrix (A'): Formed by interchanging rows and columns.
  • Symmetric matrix: A matrix satisfying A=AA = A'.
  • Skew–symmetric matrix: A matrix satisfying A=AA' = -A.
  • Important results:
  • A+AA + A' is always symmetric.
  • AAA - A' is always skew–symmetric.
  • AAAA' is always symmetric, never skew–symmetric.

 

Calculation:

Given,

A is a square matrix.

Check (i):

(A+A)=A+A(A+A')' = A' + A

⇒ same as A+AA + A'

⇒ symmetric

Check (ii):

(AA)=AA(A-A')' = A' - A

⇒ equals (AA)-(A - A')

⇒ skew–symmetric, not symmetric

Check (iii):

(AA)=(A)A=AA(AA')' = (A')' A' = AA'

⇒ symmetric, not skew–symmetric

∴ Statements (i) is true and (iii) is false, so only (i) is correct.

153

The number of real roots of the equation (x1)2+(x3)2+(x5)2=0(x - 1) ^ 2 + (x - 3) ^ 2 + (x - 5) ^ 2 = 0 is:

  1. ((a))

    0

  2. ((b))

    1

  3. ((c))

    2

  4. ((d))

    3

Show Answer
Answer: ((a))

0

Concept:

Non–negative numbers and zero condition:

  • Each expression of the form (xa)2 (x-a)^2 is always a non–negative number.
  • A sum of non–negative numbers becomes zero only when each term is zero.

Calculation:

Given,

(x1)2+(x3)2+(x5)2=0(x-1)^2 + (x-3)^2 + (x-5)^2 = 0

(x1)2=0(x-1)^2 = 0

x=1x = 1

(x3)2=0(x-3)^2 = 0

x=3x = 3

(x5)2=0(x-5)^2 = 0

x=5x = 5

All three must hold at the same time.

⇒ impossible for one x to be 1, 3, 5 simultaneously.

∴ The equation has 0 real roots.

154

The minimum value of the quadratic function f(x)=3x26x+5f(x) = 3x ^ 2 - 6x + 5 is:

  1. ((a))

    1

  2. ((b))

    2

  3. ((c))

    5

  4. ((d))

    6

Show Answer
Answer: ((b))

2

Concept:

Quadratic Function:

  • A quadratic function has the form f(x)=ax2+bx+c f(x)=ax^{2}+bx+c .
  • If a > 0, the graph opens upward and the function has a minimum value.
  • The minimum value occurs at the vertex of the parabola.
  • Vertex x-coordinate formula: x=b2a x=\frac{-b}{2a} .
  • Substituting this x in the function gives the minimum value.

 

Calculation:

Given,

f(x)=3x26x+5 f(x)=3x^{2}-6x+5

xv = (6)2×3 \frac{-(-6)}{2×3}

⇒ xv = 66 \frac{6}{6}

⇒ xv = 1

f(1) = 3(1)26(1)+5 3(1)^{2}-6(1)+5

⇒ f(1) = 36+5 3-6+5

⇒ f(1) = 2

∴ The minimum value of the function is 2.

155

The algebraic sum of deviations of 25 observations from 18 is 75, then the mean of observations is:

  1. ((a))

    18

  2. ((b))

    19

  3. ((c))

    20

  4. ((d))

    21

Show Answer
Answer: ((d))

21

Concept:

Mean of observations:

  • The mean of n observations is the average of all values.
  • Deviation of an observation from a number A is xA x - A .
  • The algebraic sum of deviations from A is (xA) \sum (x - A) .
  • Formula: (xA)=xnA \sum (x - A)=\sum x - nA .
  • If the sum of deviations is known, the mean can be found using: xˉ=A+(xA)n \bar{x} = A + \frac{\sum (x-A)}{n} .

 

Calculation:

Given,

A = 18

n = 25

(xA)=75 \sum (x-A)=75

Mean = A+(xA)n A + \frac{\sum (x-A)}{n}

⇒ Mean = 18+7525 18 + \frac{75}{25}

⇒ Mean = 18+3 18 + 3

⇒ Mean = 21

∴ The mean of the observations is 21.

156

Value of cos20cos40cos60cos80\cos 20^\circ \cos 40^\circ \cos 60^\circ \cos 80^\circ is:

  1. ((a))

    12 \frac{1}{2} \

  2. ((b))

    14 \frac{1}{4} \

  3. ((c))

    18 \frac{1}{8} \

  4. ((d))

    116\frac{1}{16}

Show Answer
Answer: ((d))

116\frac{1}{16}

Concept:

Trigonometric Product Identities:

The ratio cos θ represents the adjacent side divided by the hypotenuse.

A useful identity: cosθcos(60θ)cos(60+θ)=14cos3θ \cos \theta \cos(60^\circ-\theta)\cos(60^\circ+\theta)=\frac{1}{4}\cos 3\theta

Calculation:

Given,

cos20cos40cos60cos80 \cos 20^\circ \cos 40^\circ \cos 60^\circ \cos 80^\circ

⇒ (cos20cos40cos80)cos60 (\cos 20^\circ \cos 40^\circ \cos 80^\circ)\cos 60^\circ

Use identity: cos20cos40cos80=14cos60 \cos 20^\circ \cos 40^\circ \cos 80^\circ=\frac{1}{4}\cos 60^\circ

⇒ (cos20cos40cos80)cos60=14×12×12 (\cos 20^\circ \cos 40^\circ \cos 80^\circ)\cos 60^\circ =\frac{1}{4} × \frac{1}{2} × \frac{1}{2}

⇒ Value = 116 \frac{1}{16}

∴ The value of the expression is 1/16.

157

The least positive integer value of n, if (1+i1i)n=1\left(\frac{1+i}{1-i}\right)^n = 1 is

  1. ((a))

    1

  2. ((b))

    2

  3. ((c))

    3

  4. ((d))

    4

Show Answer
Answer: ((d))

4

Concept:

Complex numbers and powers:

  • If zn=1z^n=1 for complex zz, then zz is a root of unity.
  • Principal fact used: i4=1i^4=1 so powers of ii are periodic with period 4.

 

Calculation:

1+i1i=(1+i)(1+i)(1i)(1+i) \displaystyle \frac{1+i}{1-i} =\frac{(1+i)(1+i)}{(1-i)(1+i)}

=(1+i)212i2=1+2i+i21(1)=\frac{(1+i)^2}{1^2- i^2} =\frac{1+2i+i^2}{1-(-1)}

=1+2i12=2i2=i =\frac{1+2i-1}{2} =\frac{2i}{2}=i

⇒ So (1+i1i)n=in \left(\frac{1+i}{1-i}\right)^n = i^n

⇒ Require in=1i^n=1, smallest positive nn with this is 4.

∴ Hence, the least positive integer value of nn is 44.

158

Out of 16 points in a plane no three are in straight line except 4 points which are collinear. The number of straight lines that can be formed by joining them is:

  1. ((a))

     110

  2. ((b))

    119

  3. ((c))

    115

  4. ((d))

    121

Show Answer
Answer: ((c))

115

Calculation:

Given 16 points, 4 are collinear.

⇒ Total lines if no three collinear: (162)=16×152=120 \binom{16}{2} = \frac{16\times 15}{2} = 120

⇒ Pairs among the 4 collinear points counted as separate lines: (42)=4×32=6 \binom{4}{2} = \frac{4\times 3}{2} = 6

⇒ But those 4 points lie on a single straight line, so they produce only 1 distinct line, not 6.

⇒ Overcount due to the collinear 4 = 61=5 6 - 1 = 5

⇒ Correct number of distinct straight lines = 1205=115 120 - 5 = 115

∴ Hence, the number of straight lines is 115115.

159

For all nN,24n15n1 isn\in \text{N}, 2^{4n}-15n-1 \text{ is} is divisible by:

  1. ((a))

    225

  2. ((b))

    125

  3. ((c))

    325

  4. ((d))

    315

Show Answer
Answer: ((a))

225

Calculation:

Given expression: E=24n15n1E=2^{4n}-15n-1

24n=(16)n2^{4n}=(16)^n

Since 1616(mod225)16\equiv16\pmod{225}, compute pattern:

161=1616^1=16, 162=2563116^2=256\equiv31

163=16×31=4964616^3=16\times31=496\equiv46

164=16×46=7366116^4=16\times46=736\equiv61

Pattern continues with fixed difference.

Now evaluate E16n15n1(mod225)E\equiv 16^n-15n-1\pmod{225}.

For n = 1:

E=16151=0E=16-15-1=0

For n = 2:

E=31301=0E=31-30-1=0

For n = 3:

E=46451=0E=46-45-1=0

For n = 4:

E=61601=0E=61-60-1=0

Expression gives remainder 0 every time.

∴ Hence, the expression 24n15n12^{4n}-15n-1 is divisible by 225 for all n.

160

If p, q, r are in A.P. and x, y, z are in G.P. then xqryrpzpqx^{q-r} \cdot y^{r-p} \cdot z^{p-q} is:

  1. ((a))

    0

  2. ((b))

    1

  3. ((c))

    -1

  4. ((d))

    2

Show Answer
Answer: ((b))

1

Concept:

Progressions:

  • If p, q, r are in A.P., then they differ by a common difference d.
  • If x, y, z are in G.P., then there is a common ratio k.
  • We will use exponent laws: aman=am+na^m a^n = a^{m+n} and division rule am/an=amna^m/a^n=a^{m-n}.

 

Calculation:

Given,

p, q, r in A.P.   and   x, y, z in G.P.

Let common difference be dd.

Then q=p+d,;r=p+2dq=p+d,; r=p+2d

Let common ratio be kk.

Then y=xk,;z=xk2y=xk,; z=xk^2

Compute exponents:

qr=(p+d)(p+2d)=dq-r=(p+d)-(p+2d)=-d

rp=(p+2d)p=2dr-p=(p+2d)-p=2d

pq=p(p+d)=dp-q=p-(p+d)=-d

Evaluate expression

xqryrpzpq=xd(xk)2d(xk2)dx^{q-r}y^{r-p}z^{p-q} = x^{-d} (xk)^{2d} (xk^2)^{-d}

xdx2dk2dxdk2d x^{-d} x^{2d} k^{2d} \cdot x^{-d} k^{-2d}

xd+2dd;k2d2d x^{-d+2d-d}; k^{2d-2d}

x0k0=1 x^{0} k^{0} = 1

∴ Hence, the value is 1

161

One vertex of the equilateral triangle with centroid at origin and one side x + y - 2 = 0 is:

  1. ((a))

    (-1,-1)

  2. ((b))

    (2, 2)

  3. ((c))

    (-2,-2)

  4. ((d))

    (2,-2)

Show Answer
Answer: ((b))

(2, 2)

Concept:

Centroid & Equilateral Triangle (geometry + coordinates):

  • For a triangle with vertices P,Q,RP,Q,R, the centroid is P+Q+R3\dfrac{P+Q+R}{3}.
  • If the centroid is the origin, then P+Q+R=0P+Q+R=\mathbf{0}, so R=(P+Q)R=-(P+Q).
  • For an equilateral triangle the three side lengths are equal; we will use squared distances to avoid square roots.

 

Calculation:

If two vertices lie on the line x+y2=0x+y-2=0, we parametrize them as P=(t,,2t)P=(t,,2-t) and Q=(s,,2s)Q=(s,,2-s).

Let P=(t,2t),;Q=(s,2s)P=(t,2-t),;Q=(s,2-s)

Sum of the two points, P+Q=(t+s,;4(t+s))P+Q=(t+s,;4-(t+s))

Since centroid is origin, R=(P+Q)=(u,;u4)R=-(P+Q)=\big(-u,;u-4\big) where u=t+su=t+s

Put d=std=s-t. Then PQ2=(st)2+(ts)2=2d2PQ^2= (s-t)^2+(t-s)^2=2d^2

RP=RP=(ut,;u4(2t))=(ut,;u6+t)RP=R-P=\big(-u-t,;u-4-(2-t)\big)=(-u-t,;u-6+t)

⇒ Write u=t+s=2t+du=t+s=2t+d, so set A=3t+dA=3t+d.

⇒ Then RP2=A2+(A6)2=2A212A+36RP^2=A^2+(A-6)^2=2A^2-12A+36

RP2=PQ22A212A+36=2d2.RP^2=PQ^2\Longrightarrow 2A^2-12A+36=2d^2.

Divide by 2 and substitute A=3t+dA=3t+d:

A26A+18=d2.A^2-6A+18=d^2.

Expand with d=st,;u=t+sd=s-t,;u=t+s and simplify (algebra leads to a condition on uu):

After simplification we obtain the equation that forces u=2u=2 (the algebraic elimination of parameters gives this unique feasible sum).

Therefore P+Q=(u,;4u)=(2,2)P+Q=(u,;4-u)=(2,2)

Hence R=(P+Q)=(2,2)R=-(P+Q)=(-2,-2)

∴ Hence, the required vertex is (-2,-2).

162

The equation of a straight line passing through (1, 2) and perpendicular to x + y + 1 = 0 is:

  1. ((a))

    y - x + 1 = 0

  2. ((b))

    y + x + 1 = 0

  3. ((c))

    y - x - 1 = 0

  4. ((d))

    x - y + 2 = 0

Show Answer
Answer: ((c))

y - x - 1 = 0

Concept:

Slope and Perpendicular Lines:

  • A straight line in form x+y+1=0x+y+1=0 has slope -1.
  • A line perpendicular to another has slope equal to the negative reciprocal.
  • Use point-slope form to get the equation through a given point.

 

Calculation:

Given, point (1,2)(1,2) and line x+y+1=0x+y+1=0

Slope of x+y+1=0x+y+1=0 is 1-1.

Slope of perpendicular line is m=1m=1 (negative reciprocal).

Point-slope form: y2=1(x1)y-2=1\cdot(x-1).

Simplify: y2=x1y-2=x-1.

Rearranged: yx1=0y-x-1=0.

∴ Hence, the equation is yx1=0y-x-1=0.

163

The number of common tangent to the circles x2+y2=4x ^ 2 + y ^ 2 = 4 and

x2+y28x+12=0x ^ 2 + y ^ 2 - 8x + 12 = 0 is:

  1. ((a))

    1

  2. ((b))

    2

  3. ((c))

    3

  4. ((d))

    4

Show Answer
Answer: ((c))

3

Concept:

Common Tangents of Circles:

  • Two circles can have 0, 1, 2, 3, or 4 common tangents depending on their relative positions.
  • If distance between centres is dd and radii are r1,r2r_1,r_2, then:
  • If d > r₁ + r₂ → 4 common tangents.
  • If d = r₁ + r₂ → 3 common tangents.
  • If |r₁ − r₂| < d < r₁ + r₂ → 2 common tangents.
  • If d = |r₁ − r₂| → 1 common tangent.
  • If d < |r₁ − r₂| → 0 common tangents.

 

Calculation:

Given circles:

C1:x2+y2=4C_1: x^2+y^2=4

⇒ Centre (0,0)(0,0), radius r1=2r_1=2

C2:x2+y28x+12=0C_2: x^2+y^2-8x+12=0

Rewrite: x28x+y2=12x^2-8x+y^2=-12

x28x+16+y2=4x^2-8x+16+y^2=4

(x4)2+y2=4(x-4)^2+y^2=4

⇒ Centre (4,0)(4,0), radius r2=2r_2=2

Distance between centres: d=4d=4

Compare: d=4d=4, r1+r2=4r_1+r_2=4

Case: d=r1+r2d = r_1 + r_2 → circles touch externally.

∴ Hence, number of common tangents = 3.

164

The maximum distance of the point (10, 7) from the circlex2+y24x2y20=0 x ^ 2 + y ^ 2 - 4x - 2y - 20 = 0 is :

  1. ((a))

    10

  2. ((b))

    15

  3. ((c))

    12

  4. ((d))

    20

Show Answer
Answer: ((b))

15

Concept:

Circle — centre and radius:

  • General circle form: x2+y2+2gx+2fy+c=0x^2+y^2+2gx+2fy+c=0.
  • Centre = (g,f)(-g,-f), radius = g2+f2c\sqrt{g^2+f^2-c}.
  • Maximum distance from an external point to any point on the circle =
  • distance(point, centre) + radius.

 

Calculation:

Given circle,

x2+y24x2y20=0x^2+y^2-4x-2y-20=0

Complete squares to find centre and radius.

x24x=(x2)24x^2-4x=(x-2)^2-4.

y22y=(y1)21y^2-2y=(y-1)^2-1.

Substitute: (x2)2+(y1)25=20(x-2)^2+(y-1)^2-5=20.

(x2)2+(y1)2=25(x-2)^2+(y-1)^2=25.

⇒ Centre = (2,1)(2,1), radius = 5.

Distance from centre to given point P(10,7)P(10,7):

d=(102)2+(71)2=82+62=100=10d=\sqrt{(10-2)^2+(7-1)^2}=\sqrt{8^2+6^2}=\sqrt{100}=10.

⇒ Maximum distance = d+r=10+5=15d + r = 10 + 5 = 15.

∴ Hence, maximum distance = 15.

165

The point diametrically opposite to the point P(1, 0) on the circle x2+y2+2x+4y3=0x ^ 2 + y ^ 2 + 2x + 4y - 3 = 0 is:

  1. ((a))

    (3,-4)

  2. ((b))

     (-3,4)

  3. ((c))

     (-3,-4)

  4. ((d))

    (3,4)

Show Answer
Answer: ((c))

 (-3,-4)

Concept:

Circle — centre and radius:

  • General circle form: x2+y2+2gx+2fy+c=0x^2+y^2+2gx+2fy+c=0.
  • Centre = (g,f)(-g,-f).
  • A point diametrically opposite to point P on a circle lies exactly on the opposite end of the diameter.
  • Hence midpoint of segment joining P and opposite point = centre.
  • Formula for opposite point (x,y)(x',y') when centre is (h,k)(h,k) and P is (x,y)(x,y)x=2hx,y=2kyx' = 2h - x,\quad y' = 2k - y.

 

Calculation:

Given circle,

x2+y2+2x+4y3=0x^2+y^2+2x+4y-3=0

Compare with x2+y2+2gx+2fy+c=0x^2+y^2+2gx+2fy+c=0.

g=1,;f=2g=1,; f=2.

⇒ Centre = (1,2)(-1,-2).

Given point P = (1,0)(1,0).

Opposite point coordinates:

x=2(1)1=3x' = 2(-1) - 1 = -3.

y=2(2)0=4y' = 2(-2) - 0 = -4.

∴ Hence, the diametrically opposite point is (3,4)(-3,-4).

166

Ltx0xx\text{Lt}_{x \to 0} x^xis equal to:

  1. ((a))

    0

  2. ((b))

    1

  3. ((c))

    -1

  4. ((d))

    2

Show Answer
Answer: ((b))

1

Calculation:

Consider, L=limx0+xxL=\lim_{x\to0^+}x^x.

Write as exponential: xx=exlnxx^x=e^{x\ln x}.

Then L=limx0+exlnxL=\lim_{x\to0^+}e^{x\ln x}.

Limit of exponent: limx0+xlnx=0\lim_{x\to0^+}x\ln x=0.

Therefore L=e0=1L=e^{0}=1.

∴ Hence, limx0+xx=1\displaystyle \lim_{x\to0^+}x^x=1.

167

The value of Ltxx[tan1(x+1x+2)π4]\text{Lt}_{x \to \infty} x \left[ \tan^{-1} \left(\frac{x+1}{x+2}\right) - \frac{\pi}{4} \right]

  1. ((a))

    12 \frac{1}{2} \

  2. ((b))

    12 -\frac{1}{2} \

  3. ((c))

    1

  4. ((d))

    -1

Show Answer
Answer: ((b))

12 -\frac{1}{2} \

Calculation:

Given,

L=limxx[tan1(x+1x+2)π4]L = \lim_{x\to\infty} x\left[\tan^{-1}\left(\frac{x+1}{x+2}\right)-\frac{\pi}{4}\right]

x+1x+2=11x+2 \frac{x+1}{x+2} = 1 - \frac{1}{x+2}

Let u=11x+2u = 1 - \frac{1}{x+2}

tan1(u)π4u11+1 \tan^{-1}(u) - \frac{\pi}{4} \approx \frac{u-1}{1+1}

1/(x+2)2 \frac{-1/(x+2)}{2}

⇒ Multiply by x:

L=x(12(x+2)) L = x \left( -\frac{1}{2(x+2)} \right)

L=x2(x+2) L = -\frac{x}{2(x+2)}

L12 L \to -\frac{1}{2} as x → ∞

∴ The final value of the limit is −1⁄2.

168

If 25% of items are less than 20 and 25% are more than 40, the quartile deviation is:

  1. ((a))

    20

  2. ((b))

    30

  3. ((c))

    40

  4. ((d))

    10

Show Answer
Answer: ((d))

10

Concept:

The quartile deviation (QD) (also semi-interquartile range) is Q3Q12\dfrac{Q_3-Q_1}{2}.

Calculation:

Given,

25% items < 20 ⇒ Q1=20Q_1=20

25% items > 40 ⇒ 75% items ≤ 40 ⇒ Q3=40Q_3=40

QD=Q3Q12QD=\dfrac{Q_3-Q_1}{2}

QD=40202QD=\dfrac{40-20}{2}

QD=202=10QD=\dfrac{20}{2}=10

∴ Hence, the quartile deviation is 10.

169

The mean of 5 observations is 4 and their variance is 5.2. If three of those observations are 1, 2 and 6, the other two are:

  1. ((a))

     2 and 9

  2. ((b))

     3 and 8

  3. ((c))

    4 and 7

  4. ((d))

    5 and 6

Show Answer
Answer: ((c))

4 and 7

Concept:

Mean and Variance of a Data Set:

  • The mean of n observations is the ratio of the sum of all observations to n.
  • Formula: xˉ=xin \bar{x}=\dfrac{\sum x_i}{n}
  • The variance of observations is the mean of squared deviations from the mean.
  • Formula: σ2=(xixˉ)2n \sigma^2=\dfrac{\sum (x_i-\bar{x})^2}{n}

Calculation:

Given,

Mean xˉ=4 \bar{x}=4 , Variance σ2=5.2 \sigma^2=5.2

Three observations: 1, 2, 6

Total observations = 5

⇒ Sum = 5×4=205×4 = 20

⇒ Sum of known = 1+2+6=91+2+6=9

Let missing values be a, b

a+b=209=11a+b = 20-9 = 11

Variance formula:

(xi4)2=5×5.2=26\sum (x_i-4)^2 = 5×5.2 = 26

⇒ Known part: (14)2+(24)2+(64)2=9+4+4=17(1-4)^2+(2-4)^2+(6-4)^2=9+4+4=17

⇒ Remaining: 2617=926-17=9

(a4)2+(b4)2=9(a-4)^2+(b-4)^2 = 9

Expand: a2+b28(a+b)+32=9a^2+b^2-8(a+b)+32=9

a2+b28×11+32=9a^2+b^2 - 8×11 + 32 = 9

a2+b2=65a^2 + b^2 = 65

Also: (a+b)2=a2+b2+2ab(a+b)^2 = a^2 + b^2 + 2ab

121=65+2ab121 = 65 + 2ab

2ab=562ab = 56

ab=28ab = 28

⇒ Quadratic: t211t+28=0t^2 - 11t + 28 = 0

⇒ Roots = 4,7

∴ Hence, the other two observations are 4 and 7.

170

f(3x43x+4)=x+2, then f(x)dxf\left(\frac{3x-4}{3x+4}\right) = x+2, \text{ then } \int f(x) dx is equal to:

  1. ((a))

    ex2log3x43x+4+c e^{x-2} \log \left| \frac{3x - 4}{3x + 4} \right| + c \

  2. ((b))

    83logx1+23x+c -\frac{8}{3} \log |x - 1| + \frac{2}{3} x + c \

  3. ((c))

    83logx1+23x+c \frac{8}{3} \log |x - 1| + \frac{2}{3} x + c \

  4. ((d))

    ex2log3x+43x4+ce^{x-2} \log \left| \frac{3x + 4}{3x - 4} \right| + c

Show Answer
Answer: ((b))

83logx1+23x+c -\frac{8}{3} \log |x - 1| + \frac{2}{3} x + c \

Concept:

Functional substitution and integration:

  • Find the function f(x)f(x) by inverting the given substitution.
  • Solve for the original variable in terms of the new variable, then replace to get f(x)f(x).
  • Integrate the resulting rational function using simple algebraic decomposition (split into a polynomial + simple fraction and integrate termwise).

 

Calculation:

Given relation,

f!(3x43x+4)=x+2f!\left(\dfrac{3x-4}{3x+4}\right)=x+2

⇒ Put t=3x43x+4t=\dfrac{3x-4}{3x+4}, so f(t)=x+2f(t)=x+2.

⇒ Solve for xx in terms of tt:

t(3x+4)=3x4t(3x+4)=3x-4

3tx+4t=3x43tx+4t=3x-4

3x(t1)=4(1+t)3x(t-1)=-4(1+t)

x=4(1+t)3(t1)x=\dfrac{-4(1+t)}{3(t-1)}

⇒ Thus

f(t)=x+2=4(1+t)3(t1)+2f(t)=x+2=\dfrac{-4(1+t)}{3(t-1)}+2

Simplify numerator:

f(t)=44t+6t63(t1)=2t103(t1)f(t)=\dfrac{-4-4t+6t-6}{3(t-1)}=\dfrac{2t-10}{3(t-1)}

f(t)=2(t5)3(t1)f(t)=\dfrac{2(t-5)}{3(t-1)}

Replace tt by xx to get the function:

f(x)=2(x5)3(x1)f(x)=\dfrac{2(x-5)}{3(x-1)}

f(x),dx=23x5x1,dx\displaystyle \int f(x),dx=\frac{2}{3}\int\frac{x-5}{x-1},dx

Decompose integrand: x5x1=14x1\dfrac{x-5}{x-1}=1-\dfrac{4}{x-1}

f(x),dx=23(14x1)dx\displaystyle \int f(x),dx=\frac{2}{3}\int\left(1-\frac{4}{x-1}\right)dx

Integrate termwise:

f(x),dx=23(x4lnx1)+C\displaystyle \int f(x),dx=\frac{2}{3}\Big(x-4\ln|x-1|\Big)+C

f(x),dx=23x83lnx1+C\displaystyle \int f(x),dx=\frac{2}{3}x-\frac{8}{3}\ln|x-1|+C

∴ Hence, f(x),dx=23x83lnx1+C\displaystyle \int f(x),dx=\frac{2}{3}x-\frac{8}{3}\ln|x-1|+C

171

cosx+xsinxx(x+cosx)dx\int \frac{\cos x + x \sin x}{x (x + \cos x)} dx is equal to:

  1. ((a))

    logxx+cosx+c \log \left| \frac{x}{x + \cos x} \right| + c \

  2. ((b))

    logx+cosxx+c \log \left| \frac{x + \cos x}{x} \right| + c \

  3. ((c))

    log1x+cosx+c \log \left| \frac{1}{x + \cos x} \right| + c \

  4. ((d))

    logx+cosx+c\log |x + \cos x| + c

Show Answer
Answer: ((a))

logxx+cosx+c \log \left| \frac{x}{x + \cos x} \right| + c \

Calculation:

Let I=cosx+xsinxx(x+cosx),dxI=\displaystyle\int \frac{\cos x + x\sin x}{x(x+\cos x)},dx

⇒ Add and subtract xx in numerator:

cosx+xsinx=(x+cosx)+x(sinx1)\cos x + x\sin x = (x+\cos x) + x(\sin x -1)

⇒ So integrand splits:

cosx+xsinxx(x+cosx)=x+cosxx(x+cosx)+x(sinx1)x(x+cosx)\frac{\cos x + x\sin x}{x(x+\cos x)} =\frac{x+\cos x}{x(x+\cos x)}+\frac{x(\sin x-1)}{x(x+\cos x)}

=1x+sinx1x+cosx=\frac{1}{x}+\frac{\sin x-1}{x+\cos x}

Therefore

I=1x,dx+sinx1x+cosx,dxI=\displaystyle\int\frac{1}{x},dx +\int\frac{\sin x-1}{x+\cos x},dx

⇒ Put u=x+cosxu=x+\cos x, then du=(1sinx),dxdu=(1-\sin x),dx

⇒ Hence sinx1=du/dx\sin x-1=-du/dx, so

sinx1x+cosx,dx=duu=lnu\displaystyle\int\frac{\sin x-1}{x+\cos x},dx =\int\frac{-du}{u}=-\ln|u|

Substituting back,

I=lnxlnx+cosx+CI=\ln|x|-\ln|x+\cos x|+C

∴ Hence, cosx+xsinxx(x+cosx),dx=lnx,x+cosx,+C \displaystyle \int \frac{\cos x + x\sin x}{x(x+\cos x)},dx =\ln\left|\frac{x}{,x+\cos x,}\right|+C

172

if f(x)=a+bx+cx2,then01f(x)dxf(x) = a + bx + cx^2, then \int_{0}^{1} f(x) dx is

  1. ((a))

    12[f(0)+4f(12)+f(1)]\frac{1}{2} \left[ f(0) + 4f\left(\frac{1}{2}\right) + f(1) \right]

  2. ((b))

    16[f(0)+2f(12)+f(1)]\frac{1}{6} \left[ f(0) + 2f\left(\frac{1}{2}\right) + f(1) \right]

  3. ((c))

    16[f(0)+4f(12)+f(1)]\frac{1}{6} \left[ f(0) + 4f\left(\frac{1}{2}\right) + f(1) \right]

  4. ((d))

    12[f(0)+2f(12)+f(0)]\frac{1}{2} \left[ f(0) + 2f\left(\frac{1}{2}\right) + f(0) \right]

Show Answer
Answer: ((c))

16[f(0)+4f(12)+f(1)]\frac{1}{6} \left[ f(0) + 4f\left(\frac{1}{2}\right) + f(1) \right]

Calculation:

Given polynomial: f(x)=a+bx+cx2f(x)=a+bx+cx^2

Required integral is 01f(x),dx\displaystyle\int_{0}^{1}f(x),dx

Integrate termwise:

01a,dx=a\int_{0}^{1}a,dx=a

01bx,dx=b/2\int_{0}^{1}bx,dx=b/2

01cx2,dx=c/3\int_{0}^{1}cx^2,dx=c/3

Total integral a+b2+c3a+\frac{b}{2}+\frac{c}{3}

f(0)=af(0)=a

f(12)=a+b2+c4f(\frac12)=a+\frac{b}{2}+\frac{c}{4}

f(1)=a+b+cf(1)=a+b+c

16[a+4(a+b2+c4)+(a+b+c)]\frac16[a+4(a+\frac{b}{2}+\frac{c}{4})+(a+b+c)]

16[6a+3b+2c]\frac16[6a+3b+2c]

a+b2+c3a+\frac{b}{2}+\frac{c}{3}

∴ Hence, the value of the definite integral is 16[f(0)+4f(12)+f(1)]\frac{1}{6}[f(0)+4f(\frac12)+f(1)]

173

For the functionf(x)=x+1x,x[1,3]f(x) = x + \frac{1}{x}, x \in [1, 3] the value of C for mean value theorem is:

  1. ((a))

    3\sqrt{3}

  2. ((b))

    3-\sqrt{3}

  3. ((c))

    32\frac{3}{2}

  4. ((d))

    13\frac{1}{3}

Show Answer
Answer: ((a))

3\sqrt{3}

Concept:

Mean Value Theorem (MVT):

If a function ff is continuous on [a,b][a,b] and differentiable on (a,b) (a,b), then there exists c(a,b)c\in(a,b) such that f(c)=f(b)f(a)baf'(c)=\dfrac{f(b)-f(a)}{b-a}

Calculation:

Given f(x)=x+1xf(x)=x+\dfrac{1}{x} on [1,3][1,3].

f(3)=3+13=103f(3)=3+\dfrac{1}{3}=\dfrac{10}{3}, f(1)=1+1=2f(1)=1+1=2.

⇒ f'(c) = f(3)f(1)31=10322=432=23\dfrac{f(3)-f(1)}{3-1}=\dfrac{\tfrac{10}{3}-2}{2}=\dfrac{\tfrac{4}{3}}{2}=\dfrac{2}{3}

⇒  f(x)=11x2f'(x)=1-\dfrac{1}{x^2}

Solve 11x2=231-\dfrac{1}{x^2}=\dfrac{2}{3} for xx:

1x2=123=13\dfrac{1}{x^2}=1-\dfrac{2}{3}=\dfrac{1}{3}.

x2=3x=3x^2=3\Rightarrow x=\sqrt{3} (positive root lies in (1,3) (1,3)).

∴ Hence, the value of CC guaranteed by MVT is 3\boxed{\sqrt{3}}

174

If y=sec(tan1x)y=\sec(\tan^{-1}x)thendydxthen \frac{dy}{dx}   at x=1 is equal to

  1. ((a))

    12\frac{1}{2}

  2. ((b))

    1

  3. ((c))

    2\sqrt{2}

  4. ((d))

    12\frac{1}{\sqrt{2}}

Show Answer
Answer: ((d))

12\frac{1}{\sqrt{2}}

Calculation:

Given function: y=sec(tan1x)y=\sec(\tan^{-1}x)

⇒ Let θ=tan1(x)\theta=\tan^{-1}(x)

Then tan(θ)=x\tan(\theta)=x

Using identity, sec(θ)=1+x2\sec(\theta)=\sqrt{1+x^2}

Also, tan(θ)=x\tan(\theta)=x

Derivative: dydx=sec(θ)tan(θ)dθdx \dfrac{dy}{dx}=\sec(\theta)\tan(\theta)\dfrac{d\theta}{dx}

 dθdx=11+x2\dfrac{d\theta}{dx}=\dfrac{1}{1+x^2}

Substituting: dydx=1+x2×x×11+x2 \dfrac{dy}{dx}=\sqrt{1+x^2}\times x\times \dfrac{1}{1+x^2}

dydx=x1+x2 \dfrac{dy}{dx}= \dfrac{x}{\sqrt{1+x^2}}

⇒ At x=1x=1: dydx=12 \dfrac{dy}{dx}=\dfrac{1}{\sqrt{2}}

∴ Hence, the value of dydx\dfrac{dy}{dx} at x=1x=1 is 12\dfrac{1}{\sqrt{2}}

175

The minimum value of e(x4x3+x2)e^{(x^4-x^3+x^2)} is

  1. ((a))

    e

  2. ((b))

    1

  3. ((c))

    e2e^2

  4. ((d))

    1e\frac{1}{e}

Show Answer
Answer: ((b))

1

Concept:

Exponential Function:

  • The function ex is always positive for all real x.
  • The exponential function is increasing; therefore, the minimum value of ef(x) occurs at the minimum value of f(x).

Calculation:

Given polynomial: f(x) = x4 − x3 + x2

⇒ f(x) = x2(x2 − x + 1)

⇒ x2 ≥ 0 for all x

⇒ (x2 − x + 1) = (x − 1/2)2 + 3/4 ≥ 3/4

⇒ Therefore f(x) ≥ 0 × (3/4)

⇒ Minimum value of f(x) = 0 at x = 0

⇒ Minimum of ef(x) = e0

Hence, the minimum value is 1.

176

For any vector a\vec a , the value of (a×i^)2+(a×j^)2+(a×k^)2(\mathbf{a} \times \hat{i})^2 + (\mathbf{a} \times \hat{j})^2 + (\mathbf{a} \times \hat{k})^2

  1. ((a))

    3a23 \vec{a}^2

  2. ((b))

    a2\vec{a}^2

  3. ((c))

    2a22 \vec{a}^2

  4. ((d))

    4a24 \vec{a}^2

Show Answer
Answer: ((c))

2a22 \vec{a}^2

Concept:

Vector:

  • Vector is a physical or mathematical quantity having magnitude and direction.
  • SI unit: No fixed SI unit (depends on the physical quantity).
  • Dimensional formula: Depends on the physical quantity.
  • Important formula: A=Ax2+Ay2+Az2 |\vec A|=\sqrt{A_x^2+A_y^2+A_z^2}

Cross Product:

  • Cross product of two vectors gives a vector perpendicular to both.
  • Magnitude: A×B=ABsinθ |\vec A×\vec B|=AB\sin\theta
  • Unit: Same as product of magnitudes of the two vectors.
  • For unit vectors, i^=j^=k^=1 |\hat i|=|\hat j|=|\hat k|=1
  • Important relation:

a=axi^+ayj^+azk^ \vec a = a_x\hat i + a_y\hat j + a_z\hat k

  • Thus,

a×i^=(0,az,ay) \vec a×\hat i = (0,a_z,-a_y)

a×j^=(az,0,ax) \vec a×\hat j = (-a_z,0,a_x)

a×k^=(ay,ax,0) \vec a×\hat k = (a_y,-a_x,0)

 

Calculation:

Given vector: a=(ax,ay,az) \vec a = (a_x,a_y,a_z)

(a × î)2

a×i^2=ay2+az2 |\vec a×\hat i|^2 = a_y^2 + a_z^2

(a × ĵ)2

a×j^2=ax2+az2 |\vec a×\hat j|^2 = a_x^2 + a_z^2

(a × k̂)2

a×k^2=ax2+ay2 |\vec a×\hat k|^2 = a_x^2 + a_y^2

Sum of all three:

(ay2+az2)+(ax2+az2)+(ax2+ay2) (a_y^2+a_z^2)+(a_x^2+a_z^2)+(a_x^2+a_y^2)

2(ax2+ay2+az2) 2(a_x^2+a_y^2+a_z^2)

2a2 2|\vec a|^2

Hence, the value is 2a2.

177

The image of point (-1, 3, 4) in the plane x - 2y = 0 is:

  1. ((a))

    (173,193,4)\left(\frac{-17}{3}, \frac{-19}{3}, 4\right)

  2. ((b))

    (15, 11, 4)

  3. ((c))

    (173,193,1)\left(\frac{-17}{3}, \frac{-19}{3}, 1\right)

  4. ((d))

    (95,135,4)\left(\frac{9}{5}, \frac{-13}{5}, 4\right)

Show Answer
Answer: ((d))

(95,135,4)\left(\frac{9}{5}, \frac{-13}{5}, 4\right)

Concept:

Image of a Point in a Plane:

  • Image of a point in a plane is the reflection of that point across the given plane.
  • The formula for image of point P(x1,y1,z1)P(x_1,y_1,z_1) in plane Ax+By+Cz+D=0Ax + By + Cz + D = 0 is:

P=(x12A(Ax1+By1+Cz1+D)A2+B2+C2,;y12B(Ax1+By1+Cz1+D)A2+B2+C2,;z12C(Ax1+By1+Cz1+D)A2+B2+C2)P' = \left(x_1 - \frac{2A(Ax_1+By_1+Cz_1+D)}{A^2+B^2+C^2},; y_1 - \frac{2B(Ax_1+By_1+Cz_1+D)}{A^2+B^2+C^2},; z_1 - \frac{2C(Ax_1+By_1+Cz_1+D)}{A^2+B^2+C^2}\right)

  • Plane is a two-dimensional flat surface extending infinitely.

General form: Ax+By+Cz+D=0Ax + By + Cz + D = 0

 

Calculation:

Given point: P(1,3,4)P(-1,3,4)

Given plane: x2y=0x - 2y = 0

Rewrite plane: 1x2y+0z+0=01x - 2y + 0z + 0 = 0

A=1,;B=2,;C=0,;D=0A=1,; B=-2,; C=0,; D=0

S=Ax1+By1+Cz1+DS = Ax_1 + By_1 + Cz_1 + D

S=1(1)+(2)(3)+0(4)S = 1(-1) + (-2)(3) + 0(4)

S=16=7S = -1 - 6 = -7

⇒ Denominator = A2+B2+C2=1+4+0=5A^2 + B^2 + C^2 = 1 + 4 + 0 = 5

Coordinates of image:

x=12(1)(7)5x' = -1 - \frac{2(1)(-7)}{5}

x=1+145=95x' = -1 + \frac{14}{5} = \frac{9}{5}

y=32(2)(7)5y' = 3 - \frac{2(-2)(-7)}{5}

y=3285=135y' = 3 - \frac{28}{5} = -\frac{13}{5}

z=42(0)(7)5=4z' = 4 - \frac{2(0)(-7)}{5} = 4

∴ The image is (95,135,4)\left(\frac{9}{5},-\frac{13}{5},4\right).

178

Three numbers chosen from 1 to 20. Probability that they are not consecutive is:

  1. ((a))

    186190\frac{186}{190}

  2. ((b))

    187190\frac{187}{190}

  3. ((c))

    188190\frac{188}{190}

  4. ((d))

    183190\frac{183}{190}

Show Answer
Answer: ((b))

187190\frac{187}{190}

Concept:

Probability:

Probability gives the chance of occurrence of an event.

Formula: P(E)=Favourable outcomesTotal outcomesP(E)=\frac{\text{Favourable outcomes}}{\text{Total outcomes}}

Combination counts selections without order.

Formula: nCr=n!r!(nr)!{^nC_r}=\frac{n!}{r!(n-r)!}

Consecutive numbers are numbers occurring one after another like (1,2,3), (2,3,4).

Calculation:

Given,

Total numbers = 20

Choosing 3 numbers → combinations

Total outcomes = 20C3^{20}C_3

20C3=20×19×186=1140^{20}C_3=\frac{20×19×18}{6}=1140

Consecutive triplets count = 18

⇒ Non-consecutive outcomes = 114018=11221140-18=1122

⇒ Probability = 11221140\frac{1122}{1140}

⇒ Simplify: 11221140=187190\frac{1122}{1140}=\frac{187}{190}

∴ The probability that the three chosen numbers are not consecutive is 187190 \frac{187}{190} .

179

If the corner points of the LPP, Z = 13x - 15y subject to the constraints x + y <= 7 2x - 3y + 6 >= 0

x >= 0 and y >= 0 are (0, 0), (7, 0), (3, 4) and (0, 2), then the value of Maximum Z + 3 Minimum Z

  1. ((a))

    91

  2. ((b))

    181

  3. ((c))

    1

  4. ((d))

    -1

Show Answer
Answer: ((c))

1

Calculation:

Given objective: Z=13x15yZ=13x-15y

⇒ At (0,0): Z=0Z = 0

⇒ At (7,0): Z=13×7=91Z = 13×7 = 91

⇒ At (3,4): Z=13×315×4Z = 13×3 - 15×4

Z=3960=21Z = 39 - 60 = -21

⇒ At (0,2): Z=15×2=30Z = -15×2 = -30

⇒ Maximum Z = 9191

⇒ Minimum Z = 30-30

⇒ Required value = Max Z+3(Min Z) \text{Max Z} + 3(\text{Min Z})

91+3(30)91 + 3(-30)

9190=191 - 90 = 1

∴ Hence the required value is 11.

180

Which among the following is NOT a corner point of the LPP, maximize z = 4x + y subject to the constraints,x+y50,3x+y90,x0,y0?x+y \leq 50, 3x+y \leq 90, x \geq 0, y \geq 0 ?

  1. ((a))

    (0,50)

  2. ((b))

    (20,30)

  3. ((c))

    (50, 0)

  4. ((d))

    (30,0)

Show Answer
Answer: ((c))

(50, 0)

.Calculation:

Given constraints:

x+y50,;3x+y90,;x0,;y0x+y\le 50,;3x+y\le 90,;x\ge0,;y\ge0

Check intersections (possible corner points):

⇒ Intersection of x+y=50x+y=50 and 3x+y=903x+y=90:

⇒ Subtract: 2x=40x=202x=40\Rightarrow x=20, y=30y=30 → (20,30).

⇒ Intersections with axes:

⇒ For x+y=50x+y=50 on x-axis: (50,0).

⇒ For x+y=50x+y=50 on y-axis: (0,50).

⇒ For 3x+y=903x+y=90 on x-axis: (30,0).

Now verify feasibility 

⇒ (20,30): 20+30=5050,;320+30=909020+30=50\le50,;3·20+30=90\le90 → feasible.

⇒ (0,50): 0+50=5050,;30+50=50900+50=50\le50,;3·0+50=50\le90 → feasible.

⇒ (30,0): 30+0=3050,;330+0=909030+0=30\le50,;3·30+0=90\le90 → feasible.

⇒ (50,0): 50+0=505050+0=50\le50 but 350+0=150≰903·50+0=150\not\le90 → not feasible.

∴ Hence, (50,0) does not satisfy all constraints and so is NOT a corner point of the feasible region.

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