6500+ Quantitative Aptitude Questions and Answers With Explanation

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 16511

Q:

A man’s current age is $\frac{2}{5}$ of the age of his father. After 8 years, he will be $\frac{1}{2}$ of the age of his father. What is the age of father at now ?

A) 50	B) 40
C) 33	D) 30

Answer & Explanation Answer: B) 40

Explanation:

Let, father’s current age is A years.
Then, Man’s current age = $[(\frac{2}{5} * A)]$ years.

$[(\frac{2}{5} * A)]$ +8= $(\frac{1}{2}) (A + 8)$

2(2A+40) = 5(A+8)

A = 40

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Filed Under: Problems on Ages

23 16450

Q:

12 points lie on a circle. How many cyclic quadrilaterals can be drawn by using these points?

A) 500	B) 490
C) 495	D) 540

Answer & Explanation Answer: C) 495

Explanation:

For any set of 4 points we get a cyclic quadrilateral. Number of ways of choosing 4 points out of 12 points is $12 C_{4}$ = 495.

Therefore, we can draw 495 quadrilaterals

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Filed Under: Permutations and Combinations

3 16421

Q:

In a 48 ltr mixture, the ratio of milk and water is 5:3. How much water should be added in the mixture so as the ratio will become 3:5 ?

A) 24 lit	B) 16 lit
C) 32 lit	D) 8 lit

Answer & Explanation Answer: C) 32 lit

Explanation:

Given mixture = 48 lit

Milk in it = 48 x 5/8 = 30 lit

=> Water in it = 48 - 30 = 18 lit

Let 'L' lit of water is added to make the ratio as 3:5

=> 30/(18+L) = 3/5

=> 150 = 54 + 3L

=> L = 32 lit.

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Filed Under: Alligation or Mixture
Exam Prep: AIEEE , Bank Exams , CAT , GATE
Job Role: Bank Clerk , Bank PO

36 16390

Q:

There are 4 books on fairy tales, 5 novels and 3 plays. In how many ways can you arrange these so that books on fairy tales are together, novels are together and plays are together and in the order, books on fairytales, novels and plays ?

A) 12400	B) 17820
C) 17280	D) 12460

Answer & Explanation Answer: C) 17280

Explanation:

There are 4 books on fairy tales and they have to be put together. They can be arranged in 4! ways.

Similarly, there are 5 novels.They can be arranged in 5! ways.

And there are 3 plays.They can be arranged in 3! ways.

So, by the counting principle all of them together can be arranged in 4!´5!´3! ways = 17280

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Filed Under: Permutations and Combinations

8 16367

Q:

If the volume of the cube is 729 $c m^{3}$ , then the surface area of the cube will be

A) 486 sq.cm	B) 456 sq.cm
C) 446 sq.cm	D) 476 sq.cm

Answer & Explanation Answer: A) 486 sq.cm

Explanation:

volume = $a^{3}$ = 729;

=> a = 9

surface area= 6 $a^{2}$ = (6 x 9 x 9) = 486 sq.cm

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Filed Under: Volume and Surface Area
Exam Prep: AIEEE , Bank Exams , CAT
Job Role: Bank Clerk , Bank PO

19 16351

Q:

A shopkeeper fixes the marked price of an item 35% above its cost price. The percentage of discount allowed to gain 8% is

A) 18%	B) 20%
C) 22%	D) 24%

Answer & Explanation Answer: B) 20%

Explanation:

Let the cost price = Rs 100
then, Marked price = Rs 135

Required gain = 8%,
So Selling price = Rs 108
Discount = 135 - 108 = 27

Discount% = (27/135)*100 = 20%

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Filed Under: Profit and Loss

29 16351

Q:

In Maa Yatri Temple every devotee offers fruits to the orphans. Thus every orphan receives bananas, oranges and grapes in the ratio of 3:2:7 in terms of dozens. But the weight of a grape is 24 gm and weight of a banana and an orange are in the ratio of 4:5, while the weight of an orangeis 150gm. Find the ratio of all the three fruits in terms of weight, that an orphan gets

A) 90:75:42	B) 180:150:82
C) 75:42:90	D) None of these

Answer & Explanation Answer: D) None of these

Explanation:

Ratio of fruits (by dozen) = 3:2:7

Ratio of fruits (by weight) = 120 :150: 24

Therefore, Ratio of fruits (combined) by weight = 3 x 120 : 2 x 150 : 7 x 24 = 30 : 25 : 14

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Filed Under: Ratios and Proportions

16 16346

Quantitative Aptitude - Arithmetic Ability Questions

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