6500+ Quantitative Aptitude Questions and Answers With Explanation

Q:

If each side of a square is increased by 25%, find the percentage change in its area?

A) 65.25	B) 56.25
C) 65	D) 56

Answer & Explanation Answer: B) 56.25

Explanation:

let each side of the square be a , then area = $a^{2}$

As given that The side is increased by 25%, then

New side = 125a/100 = 5a/4

New area = ${(\frac{5 a}{4})}^{2}$

Increased area= $\frac{25 a^{2}}{16} - a^{2}$

Increase %= $\frac{[9 a^{2} / 16]}{a^{2}} * 100$ % = 56.25%

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Filed Under: Area
Exam Prep: Bank Exams
Job Role: Bank PO

941 137583

Q:

Out of 7 consonants and 4 vowels, how many words of 3 consonants and 2 vowels can be formed?

A) 25200	B) 52000
C) 120	D) 24400

Answer & Explanation Answer: A) 25200

Explanation:

Number of ways of selecting (3 consonants out of 7) and (2 vowels out of 4) = ( $7 C_{3}$ * $4 C_{2}$ )

= 210.

Number of groups, each having 3 consonants and 2 vowels = 210.

Each group contains 5 letters.

Number of ways of arranging 5 letters among themselves = 5! = 120

Required number of ways = (210 x 120) = 25200.

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Filed Under: Permutations and Combinations

257 132105

Q:

8 litres are drawn from a cask full of wine and is then filled with water. This operation is performed three more times. The ratio of the quantity of wine now left in cask to that of the water is 16 : 65. How much wine the cask hold originally?

A) 18 litres	B) 24 litres
C) 32 litres	D) 42 litres

Answer & Explanation Answer: B) 24 litres

Explanation:

Let the quantity of the wine in the cask originally be x litres

Then, quantity of wine left in cask after 4 operations = $[x {(1 - \frac{8}{x})}^{4}]$ litres

$∴ [\frac{x {(1 - \frac{8}{x})}^{4}}{x}] = \frac{16}{81}$

$\Rightarrow {[1 - \frac{8}{x}]}^{4} = {(\frac{2}{3})}^{4}$

$\Rightarrow x = 24$

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Filed Under: Alligation or Mixture

560 131490

Q:

A clock is set right at 8 a.m. The clock gains 10 minutes in 24 hours will be the true time when the clock indicates 1 p.m. on the following day?

A) 48 min. past 12.	B) 46 min. past 12.
C) 45 min. past 12.	D) 47 min. past 12.

Answer & Explanation Answer: A) 48 min. past 12.

Explanation:

Time from 8 a.m. on a day to 1 p.m. on the following day = 29 hours.

24 hours 10 min. of this clock = 24 hours of the correct clock.

$\frac{145}{6}$ hrs of this clock = 24 hours of the correct clock.

29 hours of this clock = $24 * \frac{6}{145} * 29$ hrs of the correct clock

= 28 hrs 48 min of the correct clock.

Therefore, the correct time is 28 hrs 48 min. after 8 a.m.

This is 48 min. past 12.

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Filed Under: Clocks
Exam Prep: Bank Exams
Job Role: Bank PO

681 130252

Q:

A trader mixes 26 kg of rice at Rs. 20 per kg with 30 kg of rice of other variety at Rs. 36 per kg and sells the mixture at Rs. 30 per kg. His profit percent is:

A) No profit, no loss	B) 5%
C) 8%	D) 10%

Answer & Explanation Answer: B) 5%

Explanation:

C.P. of 56 kg rice = Rs. (26 x 20 + 30 x 36) = Rs. (520 + 1080) = Rs. 1600.

S.P. of 56 kg rice = Rs. (56 x 30) = Rs. 1680.

Gain =(80/1600*100) % = 5%

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Filed Under: Profit and Loss

994 129951

Q:

A bag contains 6 white and 4 black balls .2 balls are drawn at random. Find the probability that they are of same colour.

A) 1/2	B) 7/15
C) 8/15	D) 1/9

Answer & Explanation Answer: B) 7/15

Explanation:

Let S be the sample space

Then n(S) = no of ways of drawing 2 balls out of (6+4) = $10 C_{2}$ 10 = $\frac{10 * 9}{2 * 1}$ =45

Let E = event of getting both balls of same colour

Then,n(E) = no of ways (2 balls out of six) or (2 balls out of 4)

= $6 C_{2} + 4 C_{2}$ = $\frac{6 * 5}{2 * 1} + \frac{4 * 3}{2 * 1}$ = 15+6 = 21

Therefore, P(E) = n(E)/n(S) = 21/45 = 7/15

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Filed Under: Probability

731 127970

Q:

A, B and C can do a piece of work in 24 days, 30 days and 40 days respectively. They began the work together but C left 4 days before the completion of the work. In how many days was the work completed?

A) 11 days	B) 12 days
C) 13 days	D) 14 days

Answer & Explanation Answer: A) 11 days

Explanation:

One day's work of A, B and C = (1/24 + 1/30 + 1/40) = 1/10.

C leaves 4 days before completion of the work, which means only A and B work during the last 4 days.

Work done by A and B together in the last 4 days = 4 (1/24 + 1/30) = 3/10.

Remaining Work = 7/10, which was done by A,B and C in the initial number of days.

Number of days required for this initial work = 7 days.

Thus, the total numbers of days required = 4 + 7 = 11 days.

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Filed Under: Time and Work

495 125676

Q:

Three number are in the ratio of 3 : 4 : 5 and their L.C.M. is 2400. Their H.C.F. is:

A) 40	B) 80
C) 120	D) 200

Answer & Explanation Answer: A) 40

Explanation:

Let the numbers be 3x, 4x and 5x.

Then, their L.C.M. = 60x.

So, 60x = 2400 or x = 40.

The numbers are (3 x 40), (4 x 40) and (5 x 40).

Hence, required H.C.F. = 40.

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Filed Under: HCF and LCM

420 119025

Quantitative Aptitude - Arithmetic Ability Questions

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