Army Soldier GD ASC Centre No 2 (South Bangalore) 28 March 2021 Official Paper. (Previous Year Paper)

The correct answer is Tamil Nadu.

• The hill station 'Javadi' is located in Tamil Nadu.
• Javadi hills are spread across parts of Vellore and Tiruvannamalai districts in the northern part of the state of Tamil Nadu.

Additional Information

• Mahendragiri is the highest peak in the Eastern ghats of India.
• This peak is in the Gajapati district of Odisha.
• The elevation of the peak is 1,501 m.
• Source: http://ncert.nic.in/ncerts/l/iess102.pdf

The correct answer is Karimganj.

Key Points

• Karimganj s a town in the Karimganj District of the Indian state of Assam.
• Karimganj town is located on the northern fringe of the district adjoining Bangladesh, flanked on two sides by the Kushiyara River and Longai river, Karimganj town is located just on the Bangladesh border with the river Kushiara flowing in between.
• One prominent feature of the place is a long and winding canal called Noti Khal meandering across the town.
• Karimganj became a subdivision of Sylhet District of British India in the late nineteenth century.
• It was severed from Sylhet during the Partition of India and was included in India as a part of the Cachar district in Assam.
• In 1983, Karimganj became a district of Assam.

Map of Karimganj:

The correct answer is Tamil Nadu.

• "Todas" is a tribe of Tamil Nadu.
• "Todas" is a tribal group in the higher altitudes of the Nilgiris.
• Gond is a tribe of Madhya Pradesh.
• Gond tribe is one of the largest Adivasi communities.
• The Gond called themselves Koi or Koiture.
• They inhabited the dense forests of the Vindhyas, Satpura and Mandla in the Narmada region of the Amarkantak range for centuries.

Additional Information

Important tribes of:

The correct answer is Jainism.

Key Points

• The Dilwara Temples are a group of Svetambara Jain temples.
• It is located about ​two and a half kilometres from the Mount Abu settlement.
• It is Rajasthan's only hill station and also known as Delvada Temples.
• The complex is in the midst of a range of forested hills.​

Additional Information

• Dilwara Temple complex consists of five major sections or temples devoted to five Jain Tirthankaras (Saints):
• Shri Mahaveer Swami Temple.
• Shri AdiNath Temple or Vimal Vasahi Temple.
• Shri ParshavNath Temple or Khartar Vasahi Temple.
• Shri Rishabdaoji Temple or Peethalhar Temple.
• Shri NemiNathJi Temple or Luna Vasahi Temple.

The correct answer is Meghna.​

Key Points

• The Ganges River does enter Bangladesh about 50 km below Farakka, and it is joined by several tributaries on its left side. However, the tributaries you mentioned—Mahananda, Punarbhaba, Atrai (Boral), and Karatoya—are not among them. These rivers originate in India but do not directly join the Ganges.
• The Ganges River, after entering Bangladesh, is known as the Padma River.
• It flows further south and eventually meets the Brahmaputra River near the town of Chandpur in Bangladesh.
• The combined river is then known as the Meghna River.

Additional Information

• Brahmaputra:
• It originates under the name of Siang or Dihang, from the Chemayungdung glacier of the Kailash range near the Mansarovar lake.
• It enters India west of Sadiya town in Arunachal Pradesh.
• Tributaries: Dibang, Lohit, Siang, Burhi Dihing, Tista, and Dhansari.
• It is known as Tsangpo in Tibet and Yarlung Zangbo in China.
• The river crosses Assam below Dhubri and enters Bangladesh where the river is known as Jamuna and it flows for 337 km.
• It is a perennial river and has several peculiar characteristics due to its geography and prevailing climatic conditions.
• It is flooded twice annually.
• One flood is caused by the melting of the Himalayan snow in summer and the other due to the monsoon flows.

The correct answer is Ministry of information and Broadcasting.

• Central Board of Film Certification is an independent body that provides film certificates and works under the Ministry of Information and Broadcasting, Government of India.
• The films that are screened on television and in cinemas have to be first certified by this board before the public exhibition.

Key Points

• It was formed on 15^th January 1951 under the cinematograph act, 1952 and its headquarters is in Mumbai.
• It provides four certificates namely U, U/A, A, and S.

The correct answer is Shankaracharya

• Adi Shankaracharya was considered as one of the most important philosophers and religious leaders in Indian history and the Hindu Sanatan religion and is widely revered as a religious reformer in the early 8^th century.
• Adi Shankaracharya was born on 11^th May 788 AD, at Kaladi near Kochi, Kerala.
• He is associated with Maya Theory, Advaita Vedanta (Non-Dualism), Tarak Brahma.
• He wrote a book called Bhashya - commentaries on Gita.
• Adi Shankaracharya established four major mathas in the four corners  – north (Jyotirmath), south (Sringeri, Kanchi), east (Puri), west (Dwaraka) – to propagate the philosophy of Advaita Vedanta and to promulgate the concept of Sanatana dharma.
• He died (took samadhi) at the age of 33, at Kedar tirth.

Key Points

Four mathas with their states-

The correct answer is Gopal Krishna Gokhale.

• Gopal Krishna Gokhale founded the ‘Servants of India society.
• It was formed in Pune, Maharashtra in 1905.

Key Points

• The Deccan education society was left by Gokhale to form this association.
• This association was formed with a small group of educated Indians.
• To promote social and human development and overthrow British rule in India was the objective of forming this association.
• Many campaigns for education, sanitation, and healthcare were promoted by the organization.
• Untouchability, discrimination, alcoholism, poverty, and oppression of women like issues were raised.
• Hitavada was the magazine, which was published through the association.

The correct answer is All the above factors.

• The potential for soil erosion increases if the soil has no or very little vegetative cover of plants and/or crop residues.
• Soil erosion is caused by both natural and anthropogenic factors that affect all landforms.
• Plant and residue cover protects the soil from raindrop impact and splash, tends to slow down the movement of runoff water, and allows excess surface water to infiltrate.
• The erosion-reducing effectiveness of plant and/or crop residues depends on the type, extent, and quantity of cover.
• Vegetation and residue combinations that completely cover the soil and intercept all falling raindrops at and close to the surface are the most efficient in controlling soil erosion (e.g., forests, permanent grasses).
• Partially incorporated residues and residual roots are also important as these provide channels that allow surface water to move into the soil.

Key Points

Types of erosion:-

• Soil erosion: Destruction of soil cover or removal of topsoil.
• Rill erosion: Finger-shaped grooves in the land due to water.
• Gully erosion:  Making the land bad and unsuitable for cultivation due to the enlargement of rills.
• Sheet erosion: Uniform removal of soil in thin layers by the forces of raindrops and overland flow.
• The central soil conservation board was set up by the Government of India to prepare plans for soil conservation.
• Afforestation, contour ploughing, terrace farming, control of floods, controlled grazing, crop rotation, restriction on shifting cultivation, etc are measures for soil conservation.

The correct answer is Line of Control.

• The Line of Control (LoC) is a military control line between India and Pakistan.
• For both India and Pakistan, the Line of Control is not legally recognized.

Additional Information

International Boundaries of India: 

• After China and Russia, India has the third-largest international border in the whole world.
• India is also called the 'most sensitive border' globally because it varies from infiltration to extreme climatic conditions.
• Its border in the Western part with Pakistan extends up to 3,323 km, dividing the Punjab region.
• After dividing the Punjab region, It running the boundaries up to the Rann of Kutch & Thar Desert in Rajasthan.
• Basically, India claims the entire state of Jammu and Kashmir, which includes China-administered Aksai Chin & Part of Kashmir(Pakistan Administrated).
• According to India, both are illegally occupied areas.

The correct answer is ​Football.

• Pradip Kumar Banerjee was an Indian professional footballer
• He played as a striker for the India national football team.
• He also captained the national team and later on became the coach of the national team.
• He was one of the first recipients of the Arjuna Award
• He was awarded the prestigious Padma Shri in 1990.
• Banerjee died on 20 March 2020.

The correct answer is Norman Borlaug.

Key Points

• Norman Borlaug is the father of the Green Revolution in the world.
• He was an American agricultural scientist and humanitarian.
• He is considered by some to be the "father of modern agriculture".
• He received the Nobel Peace Prize in 1970.

**Please

note:

** As India is not specified in the question so the most appropriate answer will be Norman Borlaug

• Professor M.S. Swaminathan is known as the father of the Green revolution in India.

Additional Information

• Verghese Kurien is known as the Father of the White Revolution in India.

The correct answer is Karnataka.

Key Points

• Karnataka has dethroned Kerala as the leading producer of pepper.
• Black pepper was first cultivated in Kerala (Malabar Coast of India then).
• Black pepper is dried and used as a seasoning or spice.
• It is also known by the name peppercorn.

The correct answer is Napoleon.

• In 1804, Napoleon Bonaparte crowned himself Emperor of France.
• He was the first emperor of France (1804–14/15).
• He set out to conquer neighbouring European countries, dispossessing dynasties and creating kingdoms where he placed members of his family.
• Napoleon saw his role as a moderniser of Europe. He introduced many laws such as the protection of private property and a uniform system of weights and measures provided by the decimal system.
• He was finally defeated at Waterloo in 1815.
• Many of his measures that carried the revolutionary ideas of liberty and modern laws to other parts of Europe had an impact on people long after Napoleon had left.

The correct answer is A.P.J Abdul Kalam.

• The book ‘Wings of Fire’ is authored by A.P.J Abdul Kalam.

Key Points

• The book was written by Dr. Abdul Kalam and Arun Tiwari.
• His full name is Avul Pakir Jainulabdeen Abdul Kalam.
• He served as the 11^th President of India from 2002 to 2007.
• He also helped to establish the Vikram Sarabhai Space Centre and pioneered the first space launch vehicle program.
• He is known as the Missile Man of India.

Additional Information

The correct answer is Kinetic energy.

Key Points

CONCEPT:

• Kinetic energy: The energy possessed by a body by virtue of its motion is called the kinetic energy of the body.
• A body that possesses kinetic energy can do work on some other body.

The kinetic energy of a body of mass "m" moving with a velocity "v" is given as:

\(K.E. = \frac{1}{2}mv^{2}\)

EXPLANATION:

• A bullet fired from a gun possesses very high kinetic energy because of its high velocity.
• This kinetic energy of the bullet does work on the object that it hits or strikes.
• Therefore, the bullet pierces its target because of the high kinetic energy possessed by virtue of its motion.

Additional Information

• Potential energy: The energy possessed by a body by virtue of its position or configuration is called the potential energy of the body.
• Heat energy: The energy possessed by a body as a result of the movement of its molecules.
• Acceleration: The rate of change of velocity of an object with respect to time is called its acceleration.

The correct answer is Camellia Sinensis.

Key Points 

​

Camellia Sinesis is the botanical name of tea.

The correct answer is Steel.

Key Points

CONCEPT:

• Sound: A local disturbance whose propagation is facilitated by the collisions between particles this disturbance propagates in a longitudinal wave, imagine one molecule hitting the next molecule, and then that molecule hitting the next, and so forth.
• It is a mechanical wave that needs a medium to travel.
• The speed of sound is proportional to the density of the material.
• Since the density of a solid is maximum so the speed of sound is maximum in solid.
• Speed of sound in solid (6000 m/s) > Speed of sound in liquid (1402 to 1482 m/s) > Speed of sound in gas/air (330 to 345 m/s).

EXPLANATION:

• The distances between molecules in solids are very small, i.e., solids are denser - as compared to liquids and gases.
• Because they are so close, they can collide very quickly, i.e. it takes less time for a molecule of the solid to 'bump' into its neighbor.
• Solids are packed together tighter than liquids and gases, hence sound travels fastest in solids.
• The water is liquid, so the speed of sound in water is less than that in steel.
• As the steel is solid, so the sound waves travel fastest through it and minimum in Vacuum. So option 1 is correct.

The correct answer is Archimedes.

Key Points

CONCEPT

• Density: It is defined as the mass of a body per unit volume. We can also say that how much mass it can contain in a specific volume.
• As of dense material like Iron takes more mass in a given volume than of wood.
• Mathematically it gives a formula Density (ρ) = mass (m) / Volume (V)
• SI Unit is kg/m3.
• 1m3 = 1000 liters of water.
• Flotation: It can be defined as the tendency of an object to rise to the upper levels of the fluid or to stay on the surface of the fluid.
• Sinking: The opposite of floatation is sinking and can be defined as the tendency of an object to go to the lower levels of the fluid.

EXPLANATION

Archimedes principle: 

• It is used to explain the law of flotation or upward thrust experienced when immersed in a fluid. Therefore option 4 is correct.
• The principle of Archimedes states “When a body is immersed in a liquid, an upward thrust, equal to the weight of the liquid displaced, acts on it.”
• The flotation and sinking of an object are dependent upon the relative density with each other.
• If the density of the object is more than the density of the liquid, the object will sink.
• On the other side, if the density of an object is less than the liquid, then it will float over it.
• If the density of the object and liquid is equal to each other, they are in equilibrium and float and sink both at the same time
• Therefore, the sinking or floating of an object depends on the difference in density of objects and liquid.

The correct answer is Charles Goodyear.

Key Points

EXPLANATION:

Vulcanised rubber:

• Charles Goodyear was one of the early pioneers of the tyre and the Goodyear tyre is named after him. Therefore option 4 is correct. 
• In 1844, more than 50 years before the first rubber tyres appeared on cars, Goodyear patented a process called vulcanization.
• Vulcanization refers to cross-linking at several locations. It is most commonly applied in Rubber in which sulphur is used for cross-linking polyisoprene at several locations.
• Vulcanized rubber has 3 - 5% sulphur content. The extent of stiffness of vulcanized rubber depends on the amount of sulphur added.
• During the vulcanization of natural rubber, it undergoes a cross-linking of Cis -1, 4-polyisoprene chains through the disulphide bonds.
• The vulcanization makes rubber elastic and stretchy. Therefore, vulcanized rubber is an elastomer.

The correct answer is Kidney failure.

Key Points

• Dialysis is used for patients having kidney trouble.
• Dialysis is a treatment that filters and purifies the blood using a machine.
• This helps keep your fluids and electrolytes in balance when the kidneys can't do their job.
• Dialysis has been used since the 1940s to treat people with kidney problems.
• If the kidneys fail completely, the only treatment options available are dialysis for the rest of your life or transplant.

Additional Information

• Functions of Kidney:
• kidneys prevent extra water, waste, and other impurities from accumulating in your body.
• They also help control blood pressure and regulate the levels of chemical elements in the blood.
• These elements may include sodium and potassium.
• Your kidneys even activate a form of vitamin D that improves the absorption of calcium.
• Types of Dialysis:
• Hemodialysis - 
• This process uses an artificial kidney to remove waste and extra fluid from the blood.
• The blood is removed from the body and filtered through the artificial kidney.
• The filtered blood is then returned to the body with the help of a dialysis machine.
• Peritoneal dialysis:
• Peritoneal dialysis involves surgery to implant a peritoneal dialysis (PD) catheter into your abdomen.
• The catheter helps filter your blood through the peritoneum, a membrane in your abdomen.
• During treatment, a special fluid called dialysate flows into the peritoneum.
• The dialysate absorbs waste.
• Once the dialysate draws waste out of the bloodstream, it’s drained from your abdomen.
• This process takes a few hours and needs to be repeated four to six times per day.

The correct answer is DC into AC​.

• An inverter is an electronic circuit that converts low voltage DC (direct current) into high voltage AC (alternating current) power.

Key Points

• An inverter may take the 12, 24, or 48 volts DC and convert to 230 volts AC.
• A Step-up transformer is used in home inverters.
• The main power AC is supplied to the inverter, and it is transformed into DC simultaneously, which keeps charging the battery continuously.
• There are a sensor and relay structure that always monitors the ON or OFF status of the main supply.

Additional Information

• The rectifier is an electrical device that converts A.C. to D.C.
• A frequency changer or frequency converter is an electronic or electromechanical device that converts alternating current (AC) of one frequency to alternating current of another frequency.

The correct answer is 71.33°F.

Key Points

• The Fahrenheit scale is a temperature scale that is based on the freezing point of water at 32°F and the boiling point of water at 212°F.
• The region between these two temperatures is divided into 180 equal parts i.e. each part equals 1°F.
• The absolute zero value is at -459.67°F.
• The Kelvin scale is a temperature scale that is based on the freezing point of water at 273K and the boiling point of water at 373K.
• The region between these two temperatures is divided into 100 equal parts i.e. each part equals 1K.
• The absolute zero value is at 0K.

 Temperature conversion formulas:

​CALCULATION:

Given that:

Temperature = 295 K

Kelvin to Fahrenheit: \(\frac{9}{5}(K - 273.15) + 32 = \frac{9}{5}(295 - 273.15) + 32 = 71.33 ^{\circ}F\)

The correct answer is Potash.

Key Points

• Some common name of the chemical compound, their chemical name, and chemical formula are as follows:

​

Important Points

The correct answer is the Salinometer.

Key Points

• Major instruments are following:-

The correct answer is Carbon dioxide.

Key Points

Concept:

• Greenhouse gases such as methane and carbon dioxide in the atmosphere prevent the rays of the Sun reflected from the Earth’s surface to escape the atmosphere thus trapping the radiations.

• The trapped radiations warm the Earth’s atmosphere, causing increases in the global temperature. This is called the greenhouse effect.

• And because of the increase in temperature icy bodies start melting and increases the sea level.

Explanation:

The greenhouse effect is due to an increase in the temperature of the planet due to an increase in carbon dioxide concentration of the atmosphere 

Mistake Points

Global Warming

• An increase in average temperature of the earth surface due to the greenhouse effect is called global warming
• It also refers to the increase in average temperature of the air and sea at the earth's surface
• Hence, the surface of the earth becomes warm which causes global warming
• The phenomenon is similar to that of greenhouse in which the glass-enclosed atmosphere gets heated up due to its insulation from the rest of the environment

The correct answer is Flint glass.

Key Points

• Flint glass, also called Crystal, is heavy and durable glass characterized by its brilliance, clarity, and highly refractive quality.
• In the optical glass industry, flint glass is any highly refractive lead-containing glass used to make lenses and prisms.
• Because it absorbs most ultraviolet light but comparatively little visible light, it is also used for telescope lenses.
• The light-dispersive power of flint glass can be made twice as high as that of crown glass (of conventional soda-lime composition).
• In the container glass industry, flint glass is any clear glass free of coloring.

Additional Information

• Ordinary glass:
• Soda lime glass is often referred to as ordinary glasses that are composed of silicon oxide, sodium oxide, and calcium oxide.
• A typical fundamental constituent of glass is silicon dioxide.
• Pyrex glass:
• It is also called borosilicate glass.
• It has some specific characteristics of chemical durability and more thermal resistance power.

The correct answer is fingerprints.

Key Points

• Dactylography refers to the scientific study of fingerprints as a method of identification.
• This method of identification is also called Dectyloscopy.
• Fingerprints have been a very effective method of developing the identity of the individual for a long.
• Fingerprints play a critical role in investigating criminals because the court law considers fingerprints as conclusive evidence.
• It is considered one of the most accurate methods of identification of any person.
• This method is the cheapest and works by using patterns found on the fingertips.
• The ridge pattern of two persons can never be the same.
• Moreover, there is no change in an individual’s fingerprint throughout life.

The correct answer is chlorophyll.

Key Points

• The green pigment present in leaves is called chlorophyll.
• Chlorophyll is located in a plant's chloroplasts.
• It is green in colour because it does not absorb the green wavelengths of white light.
• Phloem is tissues in plants that conducts food to other parts of the plant.
• Phloem is also called as bast.
• Xylem is a vascular tissue which conveys water and dissolved minerals to the rest of the plant.
• It also provides physical support.

The correct answer is Diamond.

Key Points

• The hardest known substance available naturally on earth is Diamond.
• Diamond is composed of pure carbon and the atomic bonding of the atoms makes it the hardest material.
• In diamond, every layer of carbon atom is bonded with strong sigma bonds.
• The presence of such strong covalent bonding between the carbon atoms arranged in a tetrahedral manner imparts rigidity to the substance making it the hardest known substance.

Important Points

• Industrial diamonds have three varieties
• 'ballas' which is a mass of minute diamond crystals difficult to cleave
• 'bort' is yellowish-grey to a black colour and massive, flawed, or irregular in shape
• 'carbonado' is black, very hard opaque, and without cleavage.
• Diamond occurrences in India have been reported since prehistoric times.
• Presently, the diamond fields of India are grouped into four regions
• South Indian tract of Andhra Pradesh, comprising parts of Anantapur, Kadapa, Guntur, Krishna, Mahabubnagar, and Kurnool districts
• Central Indian tract of Madhya Pradesh, comprising Panna belt​
• Panna is famous for diamond mines.
• It is Asia's biggest and only active diamond mine.
• The mine is run by the National Mineral Development Corporation.
• Behradin-Kodawali area in Raipur district and Tokapal, Dugapal, etc. areas in Bastar district of Chhattisgarh
• Eastern Indian tract mostly of Odisha, lying between Mahanadi and Godavari valleys.
• Hindustan Copper Ltd. at Maubhandar smelter in Singhbhum district of Jharkhand obtains silver from copper slimes.

Given:

Word = ARISE

Formula Used:

n! = n(n - 1)(n - 2).......3.2.1

Calculation

Here number of letters in word arise is 5

Different ways in which arise can be arranged is 5!

5! = 5 × 4 × 3 × 2 × 1

5! = 120

∴ The way of arrange of the word ARISE is 120.

Concept used:

Any number which can be represented in the form of p/q is rational number.

 An irrational number is a real number that cannot be expressed as a ratio of integers, for example √2

Calculation:

The product of rational and irrational numbers is always irrational if the rational number is non-zero.

Rational number = 4

Irrational number = √2

Rational × Irrational = 4√2

The product of rational and irrational numbers is always rational if the rational number is zero.

Second case Rational number = 0

Irrational number = √3

Rational × irrational = 0 × √3 = 0 

Hence, Sometimes Rational Numbers and Sometimes Irrational Numbers

Given:

A motor boat takes 2 h to travel a distance of 9 km down the current. It takes 6 h to travel the same against the current

Formula used:

Speed = Distance / Time

Speed of boat downstream = (x + y) km/hr

Speed of boat upstream = (x - y) km/hr

Calculation

Let the speed of boat in still water be x km/hr

Speed of current be y km/hr

Speed of boat downstream 

⇒ x + y = 9/2

⇒ x + y = 4.5 km/hr  - - (i)

Speed of boat against the current 

⇒ x - y = 9/6

⇒ x - y = 1.5 km/hr - - (ii)

Solving equations i and ii

Add eqn i and ii we get

⇒ x = (4.5 + 1.5) / 2

⇒ x = 3 km/hr

Substracting eqn 1 from 2 we get

⇒ y = (4.5 - 1.5) / 2

⇒ y = 1.5 km/hr

Speed of boat in still water = 3 km/hr 

Speed of boat against the current = 1.5 km/hr

Given

A person sells 320 mangoes at the cost price of 400 mangoes

Concept used

Profit = SP - CP

Profit % = (Profit/CP) × 100

Calculation

Let the cost price of one mango be Rs.1

Cost price of 320 mangoes = Rs.320

Selling price of 320 mangoes = Rs.400

Gain = 400 - 320

Gain = Rs.80

Profit% = (80/320) × 100

Profit% = (1/4) × 100

Profit% = 25%

∴ The profit percentage is 25%.

Given:

Perimeter of triangle = 600 m

Ratio of sides of triangle = 12 : 13 : 15

Concept used:

Sum of all sides of triangle = Perimeter of triangle

Calculation:

Sum of all sides of triangle 

⇒ 12x + 13x + 15x = 40x

⇒ 40x = 600

⇒ x = 15

Longest side = 15x

⇒ 15 × 15 = 225 cm

∴ The longest side is 225 cm.

Calculation:

30% of (1500 + 600) 

⇒ 30/100 × 2100

⇒ 30 × 21

⇒ 630

∴ The value of 30% of (1500 + 600) is 630.

Given:

'A' and 'B' can do a work in 30 days and 15 days respectively.

'A' starts on the work and both work alternately days after days.

Concept used:

Total work = Number of days × efficiency

Calculation

Let the total work be: Lcm of 30 and 15

Total work be 30 units.

Efficiency of A = 30/30 = 1 unit

Efficiency of B = 30/15 = 2 unit

A and B works on the alternate days

⇒ 2 days = (1 + 2) units

⇒ 2 days = 3 unit 

⇒ Multiplying 10 on both sides

30 units work done in

⇒ 2 × 10 = 20 days

∴ In 20 days will be work be completed

Calculation:

⇒ 5 × 5 = 25

⇒ 25 × 5 = 125

⇒ 25 × 5 = 625

∴ The next number is 625.

Given:

The average age of 7 boys is 20 years.

The average age of the first 6 boys is \(19\dfrac{1}{2}\) years

Concept used:

Average =  Sum of observations / Number of observations

Calculation:

Sum of Age of 7 boys 

⇒ 20 × 7 = 140 

Sum of Age of six boys

⇒ 6 × 39/2 = 117

Age of 7^th boy 

⇒ 140 - 117 = 23 years.

∴ 7^th boy is 23 years old.

Shortcut Trick

This is an alternate series (mixed series) containing two patterns.

First series (odd positions): 40, 7, 13, 19, ? (Not needed for the next term).

Second series (even positions): 31, 25, 19, 13, ?

Pattern for even positions: 31 − 6 = 25, 25 − 6 = 19, 19 − 6 = 13, 13 + 12 = 25? No, the next term in the overall sequence (9^th term) belongs to the first series.

Pattern for first series: 40 (outlier), then 7 + 6 = 13, 13 + 6 = 19, 19 + 6 = 25.

∴ The correct answer is 25.

Alternate Method

40skip→7+6→13+6→19+6→25

The sequence is a combination of two series placed alternatively. We need the 9^th term, which follows the logic of the 1^st, 3^rd, 5^th, and 7^th terms.

⇒ 1^st term = 40 (Exception or starting point)

⇒ 3^rd term = 7

⇒ 5^th term = 7 + 6 = 13

⇒ 7^th term = 13 + 6 = 19

⇒ 9^th term = 19 + 6 = 25

⇒ For verification, the even series is: 31, 25, 19, 13 (decreasing by 6 each time).

∴ The correct answer is 25.

Additional Information

Alternate Series

A series where two different logic patterns are applied to odd and even positions separately.

Arithmetic Progression (AP)

A sequence of numbers such that the difference between consecutive terms is constant. Common difference d = a_n − a_n−1.

Mixed Series Identification

If terms fluctuate (increase then decrease), check for two independent series interleaved together.

Concept used

1000 miligram = 1 gram

Calculation

1000 miligram = 1 gram

1589 miligram = ?

⇒ 1589/1000 = 1.589 grams

Given

A batsman in his 12^th inning makes a score of 63 runs and there by increase his average score by 2

Concept used

Average = Sum of the observation/Total observation

Calculation

Let the total number of runs in 11 innings be "x".

the average number of runs in 11 innings is x/11

Let the total number of runs in 12 innings after scoring 63 runs in 12^th innings be x + 63.

Average number of runs in 12^th innings is = (x + 63)/12

⇒ (x + 63)/12 = x/11 + 2

⇒ (x + 63)/12 = (x + 22)/11

⇒ 11(x + 63) = 12(x + 22)

⇒ 11x + 693 = 12x + 264

⇒ 693 - 264 = 12x - 11x

⇒ 429 = x

Average of his score after 12 innings

⇒ (x + 63)/12

⇒ (429 + 63)/12

⇒ 41

∴ His average after the 12^th innings is 41.

Alternate Method

A batsman in his 12^th inning makes a score of 63 runs

His average increases by 2 runs

Increased runs = 11 × 2

Increased runs = 22 runs

His average after 12 innings 

⇒ 63 - 22

⇒ 41

Given:

Difference of two numbers is 2

Difference of their squares is 28.

Concept used:

a2 - b2 = (a - b) (a + b)

Calculation:

Let the two number be x and y

⇒ x - y = 2  - - (i)

Difference of their squares

⇒ x2 - y2 = 28  - - (ii)

Using the formulae

⇒ 28 = 2 (x + y)

⇒ x + y = 28/2

⇒ x + y = 14

∴ The sum of the number is 14.

If there is no event then its probability is zero.

For probability some event has to happen.

Given:

Number of diagonal = 44

Formula Used:

Number of diagonal = Number of sides (Number of sides - 3)/2

Calculation:

Let assume the number of sides be x

Number of diagonal = Number of sides (Number of sides - 3)/2

⇒ 44 = x (x - 3)/2

⇒ 88 = x2 - 3x

⇒ x2 - 3x - 88 = 0

⇒ x2 - 11x + 8x - 88 = 0 

⇒ x(x - 11) + 8(x - 11) = 0

⇒ (x - 11)(x + 8) = 0

⇒ x - 11 = 0 or x + 8 = 0

⇒ x = 11, or -8

Sides can't be negative,

Side of polygon = 11

∴ The number of sides is 11.

Logic:

 

Whereas a Wheel is not a vehicle but it is a part of it.

Hence, "Wheel" is the odd word.

All except a barber require raw materials to work.

A tailor needs fabric.

A blacksmith needs iron.

A carpenter needs wood.

Hence, "barber" is different from the other three.

According to the sequence in the dictionary: 

The correct order of the given words is:

i) Bosh

ii) Checked

iii) Clear

iv) Constantly

v) Contrast

Hence, "Constantly" will be the second last word if we arrange the words in the alphabetical order.

AWAKE → ZVZJD

The pattern followed here is:

To form the code of the word, each letter of the word is replaced by its predecessor as per the English alphabetical series.

Similarly,

Hence, "EQHDMC" is the code for the word FRIEND.

Given series: 1, 5, 10, 16, 23, 31, ?

The pattern followed here is,

Therefore, the number that replace the question mark (?) is 40.

Hence, ‘40’ is the correct answer.