6500+ Quantitative Aptitude Questions and Answers With Explanation

Q:

The number of ways that 8 beads of different colours be strung as a necklace is

A) 2520	B) 2880
C) 4320	D) 5040

Answer & Explanation Answer: A) 2520

Explanation:

The number of ways of arranging n beads in a necklace is $\frac{(n - 1)!}{2} = \frac{(8 - 1)!}{2} = \frac{7!}{2}$ = 2520

(since n = 8)

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Filed Under: Permutations and Combinations
Exam Prep: AIEEE , Bank Exams , CAT
Job Role: Bank Clerk , Bank PO

27 16350

Q:

If July 9th,2013 falls on Sunday then Jan 7th,2014 falls on which day?

A) Sunday	B) Saturday
C) Monday	D) Friday

Answer & Explanation Answer: A) Sunday

Explanation:

First,we count the number of odd days for the left over days in the given period.Here,given period is 09-07-2013 to 07-01-2014

Month	Jul	Aug	Sep	Oct	Nov	Dec	Jan
Days	22	31	30	31	30	31	7
Odd Days	1	3	2	3	2	3	0

Therefore, No. of Odd Days = 1 + 3 + 2 + 3 + 2 + 3 + 0 = 14 = 0 odd days

So, given day Sunday + 0 = Saturday is the required result.

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Filed Under: Calendar

86 16350

Q:

The third proportional to $(x^{2} - y^{2})$ and $(x - y)$ is :

A) (x + y )	B) (x - y)
C) (x + y) / ( x - y)	D) (x -y) / ( x + y)

Answer & Explanation Answer: D) (x -y) / ( x + y)

Explanation:

Let the third proportional to $(x^{2} - y^{2})$ and $(x - y)$ be z. Then,

$(x^{2} - y^{2}) : (x - y) : : (x - y) : z$

$= > (x^{2} - y^{2}) * z = {(x - y)}^{2}$

=> z= $\frac{{(x - y)}^{2}}{(x^{2} - y^{2})} = \frac{(x - y)}{(x + y)}$

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Filed Under: Ratios and Proportions

65 16337

Q:

A box contains 100 balls, numbered from 1 to 100. If three balls are selected at random and with replacement from the box, what is the probability that the sum of the three numbers on the balls selected from the box will be odd?

A) 1/6	B) 1/3
C) 1/2	D) 1/4

Answer & Explanation Answer: C) 1/2

Explanation:

P(odd) = P (even) = $\frac{1}{2}$ 1(because there are 50 odd and 50 even numbers)

Sum or the three numbers can be odd only under the following 4 scenarios:

Odd + Odd + Odd = $\frac{1}{2} * \frac{1}{2} * \frac{1}{2}$ = $\frac{1}{8}$

Odd + Even + Even = $\frac{1}{2} * \frac{1}{2} * \frac{1}{2}$ = $\frac{1}{8}$

Even + Odd + Even = $\frac{1}{2} * \frac{1}{2} * \frac{1}{2}$ = $\frac{1}{8}$

Even + Even + Odd = $\frac{1}{2} * \frac{1}{2} * \frac{1}{2}$ = $\frac{1}{8}$

Other combinations of odd and even will give even numbers.

Adding up the 4 scenarios above:

= $\frac{1}{8}$ + $\frac{1}{8}$ + $\frac{1}{8}$ + $\frac{1}{8}$ = $\frac{4}{8}$ = $\frac{1}{2}$

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Filed Under: Probability

10 16330

Q:

The average of any 5 consecutive odd natural numbers is k . If two more such numbers , just next to the previous 5 numbers are added , the new average becomes

A) 2(k+1)	B) 2k-3
C) 2k+1	D) k+2

Answer & Explanation Answer: D) k+2

Explanation:

The 5 consecutive odd numbers whose average is k are (k-4), (k-2), k, (k+2), (k+4)

Again the average of (k-4), (k-2), k, (k+2), (k+4), (k+6), (k+8) is (k+2)

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Filed Under: Average

14 16329

Q:

Two trains having equal lengths, take 10 seconds and 15 seconds respectively to cross a post. If the length of each train is 120 meters, in what time (in seconds) will they cross each other when traveling in opposite direction?

A) 10	B) 25
C) 12	D) 20

Answer & Explanation Answer: C) 12

Explanation:

Speed of train 1 = $(\frac{120}{10}) m / s e c$ = 12 m/sec

Speed of train 2 = $(\frac{120}{15}) m / s e c$ = 8 m/sec

if they travel in opposite direction, relative speed = 12 + 8 = 20 m/sec

distance covered = 120 + 120 = 240 m

time = distance/speed = 240/20 = 12 sec

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Filed Under: Problems on Trains

22 16324

Q:

A person goes to his office at 1/3rd of the speed at which he returns from his office. If the average speed during the whole trip is 12 m /h . what is the speed of the person while he was going to his office?

A) 10	B) 6
C) 8	D) can't be determined

Answer & Explanation Answer: C) 8

Explanation:

u = k , v= 3k

$∴ \frac{2 u v}{u + v} \Rightarrow \frac{2 \times k \times 3 k}{(k + 3 k)} = 12$ => k = 8km/h

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Filed Under: Time and Distance

12 16305

Q:

Given below are the ages in yrs of a group of children. What is the medium age?

7, 9, 8, 6 , 5, 3, 9, 2

A) 6.5	B) 5
C) 6.125	D) 6

Quantitative Aptitude - Arithmetic Ability Questions

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