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Question 241

Delhi Police Driver 2022• Numerical Ability

The value of \(1.\overline{36} +3.\overline{24} + 1.\overline{33} \) is:

  1. AOption (a)

    \(\frac{196}{32}\)

  2. BOption (b)

    \(\frac{176}{29}\)

  3. COption (c)

    \(\frac{186}{29}\)

  4. DOption (d)

    \(\frac{196}{33}\)

View answer & explanation

Correct answer

Answer: (d)D.

\(\frac{196}{33}\)

Why this answer is correct

Given:

The value of 1.\(\overline{36}\) + 3.\(\overline{24}\) + 1.\(\overline{33}\) is:

Formula used:

To convert a repeating decimal into a fraction:

If the repeating part is "x", use the formula: \(\text{Number} = \frac{\text{Non-repeating + Repeating}}{\text{Denominator}}\)

Calculation:

1.\(\overline{36}\) = 1 + \(\frac{36}{99}\) = \(\frac{135}{99}\)

3.\(\overline{24}\) = 3 + \(\frac{24}{99}\) = \(\frac{321}{99}\)

1.\(\overline{33}\) = 1 + \(\frac{33}{99}\) = \(\frac{132}{99}\)

Now, summing them up:

⇒ 1.\(\overline{36}\) + 3.\(\overline{24}\) + 1.\(\overline{33}\) = \(\frac{135}{99} + \frac{321}{99} + \frac{132}{99}\)

⇒ \(\frac{135 + 321 + 132}{99} = \frac{588}{99}\)

⇒ Simplify: \(\frac{588}{99} = \frac{196}{33}\)

∴ The correct answer is option (4).

Question 242

Delhi Police Driver 2022• Numerical Ability

A field is 120 m long and 50 m wide. How many times (rounded off to two decimal places) is its perimeter to the length of its diagonal?

  1. AOption (a)

    1.31

  2. BOption (b)

    2.62

  3. COption (c)

    3.42

  4. DOption (d)

    3.14

View answer & explanation

Correct answer

Answer: (b)B.

2.62

Why this answer is correct

Given:

Length of the field (L) = 120 m

Width of the field (W) = 50 m

Formula used:

Perimeter of rectangle = 2 × (L + W)

Diagonal of rectangle = √(L2 + W2)

Ratio = Perimeter / Diagonal

Calculation:

Perimeter = 2 × (120 + 50)

⇒ Perimeter = 2 × 170

⇒ Perimeter = 340 m

Diagonal = √(1202 + 502)

⇒ Diagonal = √(14400 + 2500)

⇒ Diagonal = √16900

⇒ Diagonal = 130 m

Ratio = Perimeter / Diagonal

⇒ Ratio = 340 / 130

⇒ Ratio = 2.62

∴ The correct answer is option (2).

Question 243

Delhi Police Driver 2022• Numerical Ability

A dishonest dealer professes to sell his items at cost price but uses a weight of 945 grams for a kilogram. Find his gain percentage. (Correct to 2 decimal places)

  1. AOption (a)

    7.75%

  2. BOption (b)

    6.25%

  3. COption (c)

    9.25% 

  4. DOption (d)

    5.82%

View answer & explanation

Correct answer

Answer: (d)D.

5.82%

Why this answer is correct

Given:

The dealer claims to sell at cost price but uses 945 grams instead of 1 kilogram (1000 grams).

Formula used:

Gain Percentage = Profit/Cost Price × 100

Profit = Selling Price - Cost Price

Calculation:

Cost Price for 1000 grams = ₹1000

Weight actually given = 945 grams

Selling Price for 945 grams = ₹1000

Cost Price for 945 grams = 945/1000 × ₹1000 = ₹945

Profit = Selling Price - Cost Price

⇒ Profit = ₹1000 - ₹945 = ₹55

Gain Percentage = Profit/Cost Price × 100

⇒ Gain Percentage = 55/945 × 100

⇒ Gain Percentage = 5.82%

∴ The correct answer is option (4).

Question 244

Delhi Police Driver 2022• Numerical Ability

The price of an article is reduced by 10% and its daily sale increased by 15%. Find the net percent effect on the daily sale.

  1. AOption (a)

     2.5% decrease 

  2. BOption (b)

    2.5% increase

  3. COption (c)

     3.5% decrease

  4. DOption (d)

     3.5% increase 

View answer & explanation

Correct answer

Answer: (d)D.

 3.5% increase 

Why this answer is correct

Given:

The price of an article is reduced by 10% and its daily sale increased by 15%.

Formula used:

Net percentage effect = (x + y + (x × y)/100)

Where:

x = percentage change in price = -10%

y = percentage change in daily sale = +15%

Calculation:

⇒ Net effect = (-10) + 15 + ((-10) × 15)/100

⇒ Net effect = 5 + (-150)/100

⇒ Net effect = 5 - 1.5

⇒ Net effect = 3.5% increase

∴ The correct answer is option (4).

Question 245

Delhi Police Driver 2022• Numerical Ability

An amount becomes ₹40,84,101 at 20% per annum for 15 months, which is compounded quarterly. What was the principal? 

  1. AOption (a)

    ₹44,00,000 

  2. BOption (b)

    ₹40,00,000

  3. COption (c)

    ₹32,00,000

  4. DOption (d)

    ₹36,00,000

View answer & explanation

Correct answer

Answer: (c)C.

₹32,00,000

Why this answer is correct

Given:

Amount (A) = ₹40,84,101

Rate (r) = 20% per annum

Time (t) = 15 months (1.25 years)

Compounding frequency = Quarterly

Formula used:

A = P(1 + r/(100 × n))n×t

Where,

A = Amount

P = Principal

r = Rate of interest per annum

n = Number of times compounding in a year

t = Time in years

Calculations:

₹40,84,101 = P(1 + 20/(100 × 4))4×1.25

⇒ ₹40,84,101 = P(1 + 20/400)5

⇒ ₹40,84,101 = P(1 + 0.05)5

⇒ ₹40,84,101 = P(1.05)5

⇒ ₹40,84,101 = P × 1.276281

⇒ P = ₹40,84,101 / 1.276281

⇒ P = ₹32,00,000

∴ The correct answer is option (3).

Question 246

Delhi Police Driver 2022• Numerical Ability

If the outer diameter of a spherical shell is 18 cm and inner diameter is 12 cm, then find the volume of metal contained in the shell (take π=3.14) correct to two places of decimal.

  1. AOption (a)

    2199.88 cm³ 

  2. BOption (b)

    2147.76 cm³

  3. COption (c)

    2189.75 cm³

  4. DOption (d)

    2153.76 cm³

View answer & explanation

Correct answer

Answer: (b)B.

2147.76 cm³

Why this answer is correct

Given:

Outer diameter of the spherical shell = 18 cm

Inner diameter of the spherical shell = 12 cm

π = 3.14

Formula Used:

Volume of a sphere = (4/3) × π × r3

Volume of the spherical shell = Volume of outer sphere - Volume of inner sphere

Calculations:

Outer radius (R) = 18/2 = 9 cm

Inner radius (r) = 12/2 = 6 cm

Volume of outer sphere = (4/3) × 3.14 × 93

⇒ Volume of outer sphere = (4/3) × 3.14 × 729

⇒ Volume of outer sphere = 3052.08 cm3

Volume of inner sphere = (4/3) × 3.14 × 63

⇒ Volume of inner sphere = (4/3) × 3.14 × 216

⇒ Volume of inner sphere = 904.32 cm3

Volume of the spherical shell = Volume of outer sphere - Volume of inner sphere

⇒ Volume of the spherical shell = 3052.08 - 904.32

⇒ Volume of the spherical shell = 2147.76 cm3

∴ The correct answer is option (2).

Question 247

Delhi Police Driver 2022• Numerical Ability

A policeman starts to chase a thief. When the thief goes 12 steps, the policeman moves 9 steps. 6 steps of the policeman is equal to 9 steps of the thief. The ratio of the speed of the thief to that of the policeman is: 

  1. AOption (a)

    3 : 2

  2. BOption (b)

    2 : 3

  3. COption (c)

    9 : 8

  4. DOption (d)

    8 : 9

View answer & explanation

Correct answer

Answer: (d)D.

8 : 9

Why this answer is correct

Given:

A policeman starts to chase a thief. When the thief goes 12 steps, the policeman moves 9 steps.

6 steps of the policeman = 9 steps of the thief.

Formula used:

Speed = Distance / Time

To find the ratio of the speed of the thief to that of the policeman:

Speed of thief / Speed of policeman = (Distance covered by thief in 1 step) / (Distance covered by policeman in 1 step).

Calculation:

Let the distance covered by the thief in 1 step = T and the distance covered by the policeman in 1 step = P.

6P = 9T

⇒ P / T = 9 / 6

⇒ P / T = 3 / 2

In the given time, the thief takes 12 steps, and the policeman takes 9 steps:

Speed of thief / Speed of policeman = (12 × T) / (9 × P)

⇒ Speed of thief / Speed of policeman = (12 × T) / (9 × (3T / 2))

⇒ Speed of thief / Speed of policeman = (12) / (9 × 3 / 2)

⇒ Speed of thief / Speed of policeman = (12 × 2) / (27)

⇒ Speed of thief / Speed of policeman = 24 / 27

⇒ Speed of thief / Speed of policeman = 8 / 9 = 8 : 9

∴ The correct answer is  8 : 9

Question 248

Delhi Police Driver 2022• Numerical Ability

If 5 kg of salt costing Rs. 21 per kg and 3 kg of salt costing Rs. 25 per kg are mixed, then what is the average cost of the resulting mixture per kilogram?

  1. AOption (a)

    Rs. 23.5 

  2. BOption (b)

    Rs. 21.5

  3. COption (c)

    Rs. 22.5

  4. DOption (d)

    Rs. 24.0

View answer & explanation

Correct answer

Answer: (c)C.

Rs. 22.5

Why this answer is correct

Given:

Weight of first type of salt = 5 kg

Cost of first type of salt per kg = Rs. 21

Weight of second type of salt = 3 kg

Cost of second type of salt per kg = Rs. 25

Formula used:

Average cost per kg = (Total cost of mixture) / (Total weight of mixture)

Calculation:

Total cost of mixture = (Weight of first salt × Cost of first salt per kg) + (Weight of second salt × Cost of second salt per kg)

⇒ Total cost = (5 × 21) + (3 × 25)

⇒ Total cost = 105 + 75

⇒ Total cost = 180

Total weight of mixture = 5 + 3 = 8 kg

Average cost per kg = Total cost / Total weight

⇒ Average cost per kg = 180 / 8

⇒ Average cost per kg = 22.5

∴ The correct answer is option (3).

Question 249

Delhi Police Driver 2022• Numerical Ability

A store dealer sells an article, whose marked price is ₹7,200. The cost price of the article is 70% below the marked price. Two successive equal discounts of 25% and 25% are offered to a customer. The customer gets a further 18% discount on his net payment, if the customer redeems a coupon issued by the store previously to celebrate the store’s 5th Anniversary. What is the profit percentage (to the nearest integer) earned by the dealer in this transaction? 

  1. AOption (a)

    58%

  2. BOption (b)

    68%

  3. COption (c)

    64%

  4. DOption (d)

    54%

View answer & explanation

Correct answer

Answer: (d)D.

54%

Why this answer is correct

Given:

Marked price (MP) = ₹7,200

Cost price (CP) = 70% below the marked price

Successive discounts = 25% and 25%

Further discount = 18% on net payment

Formula used:

Cost Price (CP) = MP × (1 - Discount %)

Successive Discount = MP × (1 - First Discount %) × (1 - Second Discount %)

Further Discount = SP × (1 - Discount %)

Profit Percentage = [(SP - CP) / CP] × 100

Calculations:

Cost Price:

⇒ CP = 7200 × (1 - 70/100)

⇒ CP = 7200 × 0.3 = ₹2,160

Selling Price after successive discounts:

⇒ SP after first two discounts = 7200 × (1 - 25/100) × (1 - 25/100)

⇒ SP after first two discounts = 7200 × 0.75 × 0.75

⇒ SP after first two discounts = ₹4,050

Selling Price after further discount:

⇒ Final SP = SP after first two discounts × (1 - 18/100)

⇒ Final SP = 4050 × 0.82

⇒ Final SP = ₹3,321

Profit Percentage:

⇒ Profit = Final SP - CP

⇒ Profit = 3321 - 2160 = ₹1,161

⇒ Profit Percentage = (Profit / CP) × 100

⇒ Profit Percentage = (1161 / 2160) × 100

⇒ Profit Percentage ≈ 53.75% = 54%

∴ The correct answer is 54%

Question 250

Delhi Police Driver 2022• Numerical Ability

6 men and 4 boys can finish a work in 20 days, and the same is finished in 24 days by 4 men and 6 boys. In how many days can 2 boys and 1 man finish the work? 

  1. AOption (a)

    75.8

  2. BOption (b)

    78.5

  3. COption (c)

    85.7

  4. DOption (d)

    87.5

View answer & explanation

Correct answer

Answer: (c)C.

85.7

Why this answer is correct

Given:

6 men and 4 boys can finish a work in 20 days.

4 men and 6 boys can finish the same work in 24 days.

We need to find the number of days 2 boys and 1 man can finish the work.

Formula used:

Work = (Efficiency × Time)

Efficiency of a group = Total work / Time

Calculation:

Let the efficiency of 1 man be m and 1 boy be b.

Total work = Efficiency × Time

For 6 men and 4 boys:

Work = Efficiency × Time

⇒ (6m + 4b) × 20

⇒ Total work = 120m + 80b

For 4 men and 6 boys:

Work = Efficiency × Time

⇒ (4m + 6b) × 24

⇒ Total work = 96m + 144b

Equating the two total works:

⇒ 120m + 80b = 96m + 144b

⇒ 24m = 64b

⇒ m = 64b / 24

⇒ m = 8b / 3

Now, find the efficiency of 2 boys and 1 man:

Efficiency = (1m + 2b)

⇒ Efficiency = (8b / 3) + 2b

⇒ Efficiency = (8b / 3) + (6b / 3)

⇒ Efficiency = 14b / 3

Total work from the first case:

Total work = (6m + 4b) × 20

⇒ Total work = 120m + 80b

Substitute m = 8b / 3:

⇒ Total work = 120(8b / 3) + 80b

⇒ Total work = (960b / 3) + (240b / 3)

⇒ Total work = 1200b / 3

⇒ Total work = 400b

Time for 2 boys and 1 man:

Time = Total work / Efficiency

⇒ Time = 400b / (14b / 3)

⇒ Time = (400b × 3) / 14b

⇒ Time = 1200 / 14

⇒ Time = 85.7 days

∴ The correct answer is option (3).