6500+ Quantitative Aptitude Questions and Answers With Explanation

Q:

In an examination, a student scores 4 marks for every correct answer and loses 1 mark for every wrong answer. If he attempts all 60 questions and secures 130 marks, the no of questions he attempts correctly is :

A) 35	B) 38
C) 40	D) 42

Answer & Explanation Answer: B) 38

Explanation:

Let the number of correct answers be X.

Number of incorrect answers = (60 – X).

4x – (60 – x) = 130

=> 5x = 190

=> x = 38

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Filed Under: Simplification

261 85769

Q:

The average of 7 consecutive numbers is 20. The largest of these numbers is :

A) 21	B) 22
C) 23	D) 24

Answer & Explanation Answer: C) 23

Explanation:

Let the numbers be x, x + 1, x + 2, x + 3, x + 4, x + 5 and x + 6,

Then (x + (x + 1) + (x + 2) + (x + 3) + (x + 4) + (x + 5) + (x + 6)) / 7 = 20.

or 7x + 21 = 140 or 7x = 119 or x =17.

Latest number = x + 6 = 23.

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Filed Under: Average

249 85378

Q:

If each edge of a cube is increased by 50%, find the percentage increase in Its surface area

A) 125%	B) 150%
C) 175%	D) 110%

Answer & Explanation Answer: A) 125%

Explanation:

Let the edge = a cm

So increase by 50 % = a + a/2 = 3a/2

Total surface Area of original cube = $6 a^{2}$

TSA of new cube = $6 {(\frac{3 a}{2})}^{2}$ = $6 (\frac{9 a^{2}}{4})$ = $13.5 a^{2}$

Increase in area = $13.5 a^{2} - 6 a^{2}$ = $7.5 a^{2}$

$7.5 a^{2}$ Increase % = $\frac{7.5 a^{2}}{6 a^{2}} \times 100$ = 125%

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Filed Under: Volume and Surface Area

477 85246

Q:

A, B, C started a business with their investments in the ratio 1:3 :5. After 4 months, A invested the same amount as before and B as well as C withdrew half of their investments. The ratio of their profits at the end of the year is :

A) 1 : 2 : 3	B) 3 : 4 : 15
C) 3 : 5 : 10	D) 5 : 6 : 10

Answer & Explanation Answer: D) 5 : 6 : 10

Explanation:

Let their initial investments be x, 3x and 5x respectively. Then,

A:B:C = (x*4+2x*8) : (3x*4+(3x/2)*8) : (5x*4+(5x/2)*8)

20x : 24x : 40x = 5 : 6 : 10

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Filed Under: Partnership

203 84117

Q:

In a 100 m race, A beats B by 10 m and C by 13 m. In a race of 180 m, B will beat C by:

A) 5.4m	B) 4.5m
C) 5m	D) 6m

Answer & Explanation Answer: D) 6m

Explanation:

A : B = 100 : 90.

A : C = 100 : 87.

B/C = (B/A*A/C) = (90/100*100/87) = 30/29

When B runs 30 m, C runs 29 m.

When B runs 180 m, C runs (29/30*180)m =174m

B beats C by (180 - 174) m = 6 m.

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Filed Under: Races and Games

102 82229

Q:

The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero ?

A) 0	B) -1
C) 1	D) none of these

Answer & Explanation Answer: A) 0

Explanation:

Average of 20 numbers = 0.

Sum of 20 numbers = (0 * 20) = 0.

It is quite possible that 19 of these numbers may be positive and if their sum is a, then 20th number is (- a).

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Filed Under: Average

271 82106

Q:

Insert the missing number.

8, 7, 11, 12, 14, 17, 17, 22, (....)

A) 20	B) 22
C) 24	D) 27

Answer & Explanation Answer: A) 20

Explanation:

There are two series (8, 11, 14, 17, 20) and (7, 12, 17, 22) increasing by 3 and 5 respectively.

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Filed Under: Odd Man Out

110 82062

Q:

Two dice are tossed. The probability that the total score is a prime number is:

A) 5/12	B) 1/6
C) 1/2	D) 7/9

Answer & Explanation Answer: A) 5/12

Explanation:

Clearly, n(S) = (6 x 6) = 36.

Let E = Event that the sum is a prime number.

Then E= { (1, 1), (1, 2), (1, 4), (1, 6), (2, 1), (2, 3), (2, 5), (3, 2), (3, 4), (4, 1), (4,3),(5, 2), (5, 6), (6, 1), (6, 5) }

n(E) = 15.

P(E) = n(E)/n(S) = 15/36 = 5/12.

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Filed Under: Probability

199 81751

Quantitative Aptitude - Arithmetic Ability Questions

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