6500+ Quantitative Aptitude Questions and Answers With Explanation

Q:

How many cubes of 10cm edge can be put in a cubical box of 1m edge

A) 10	B) 100
C) 1000	D) 10000

Answer & Explanation Answer: C) 1000

Explanation:

Number of cubes= (100x100x100) / (10x10x10)= 1000

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Filed Under: Volume and Surface Area
Exam Prep: Bank Exams
Job Role: Bank PO

45 16547

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 16537

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 16526

Q:

The average age of a group of persons going for picnic is 16 years. Twenty new persons with an average age of 15 years join the group on the spot due to which their average age becomes 15.5 years. The number of persons initially going for picnic is :

A) 15	B) 20
C) 23	D) 24

Answer & Explanation Answer: B) 20

Explanation:

Let the initial number of persons be x. Then,

16x + 20 * 15 = 15.5 (x + 20) <=> 0.5x = 10 <=> x = 20.

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Filed Under: Average

19 16518

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 16510

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 16502

Q:

The LCM of the three numbers 16, 28 and 42 is

A) 168	B) 2
C) 252	D) 336

Answer & Explanation Answer: D) 336

Explanation:

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Filed Under: HCF and LCM
Exam Prep: Bank Exams

1 16493

Q:

217 x 217 + 183 x 183 = ?

A) 84521	B) 87487
C) 80578	D) 78458

Answer & Explanation Answer: C) 80578

Explanation:

${(217)}^{2} + {(183)}^{2}$

= ${(200 + 17)}^{2} + {(200 - 17)}^{2}$

It is in the form of ${(a + b)}^{2} + {(a - b)}^{2} = 2 (a^{2} + b^{2})$

= 2(40000 + 289) = 80578.

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Filed Under: Simplification
Exam Prep: GATE , CAT , Bank Exams , AIEEE
Job Role: Bank PO , Bank Clerk

22 16485

Quantitative Aptitude - Arithmetic Ability Questions

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