Quantitative Aptitude - Arithmetic Ability Questions

Q:

If the radius of a circle is decreased by 50%, find the percentage decrease in its area.

A) 55% B) 65%
C) 75% D) 85%
 
Answer & Explanation Answer: C) 75%

Explanation:

Let original radius = R. 

 

New radius = 50100R50100R 

 

Original area =R2  and new area = πR2

 

3πR24*1πR2*100 

 

Decrease in area = πR22=πR24 = 75%

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Q:

One card is drawn at random from a pack of 52 cards. What is the probability that the card drawn is a face card (Jack, Queen and King only)?

A) 3/13 B) 1/13
C) 3/52 D) 9/52
 
Answer & Explanation Answer: A) 3/13

Explanation:

Clearly, there are 52 cards, out of which there are 12 face cards.

P (getting a face card) = 12/52=3/13.

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Q:

A sum of money lent at compound interest for 2 years at 20% per annum would fetch Rs.482 more, if the interest was payable half yearly than if it was payable annually . The sum is

A) 10000 B) 20000
C) 40000 D) 50000
 
Answer & Explanation Answer: B) 20000

Explanation:

Let sum=Rs.x

 

C.I. when compounded half yearly = x1+101004-x=464110000

 

C.I. when compounded annually =x201002-x=1125

 464110000x-1125x=482

 

=> x=20000

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Filed Under: Compound Interest
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Q:

The salaries of A, B, and C are in the ratio of 1 : 2 : 3. The salary of B and C together is Rs. 6000. By what percent is the salary of C more than that of A?

A) 100 % B) 200%
C) 300% D) 600%
 
Answer & Explanation Answer: B) 200%

Explanation:

Let the salaries of A, B, C be x, 2x and 3x respectively.

Then,2x + 3x = 6000  => x = 1200.

A's salary = Rs. 1200, B's salary = Rs. 2400, and Cs salary Rs. 3600.
Excess of C's salary over A's=[ (2400 /1200) x 100] = 200%.

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Filed Under: Ratios and Proportions

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Q:

What is the value of (√2/3 - cosec60)?

 

A) (√6-6)/3√3 B) (2-2√3)/√3  
C) (1-√6)/√2   D) (4-√3)/2√3
 
Answer & Explanation Answer: A) (√6-6)/3√3

Explanation:
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Filed Under: Simplification
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Q:

Cosec (90 - θ)

 

A) tan θ B) cot θ
C) sec θ D) cos θ
 
Answer & Explanation Answer: C) sec θ

Explanation:
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Q:

A bag contains 6 black and 8 white balls. One ball is drawn at random. What is the probability that the ball drawn is white?

A) 3/7 B) 4/7
C) 1/8 D) 3/4
 
Answer & Explanation Answer: B) 4/7

Explanation:

Let number of balls = (6 + 8) = 14.

Number of white balls = 8.

P (drawing a white ball) = 8 /14 = 4/7.

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Q:

In the below word how many words are there in which R and W are at the end positions?

RAINBOW

A) 120 B) 180
C) 210 D) 240
 
Answer & Explanation Answer: D) 240

Explanation:

When R and W are the first and last letters of all the words then we can arrange them in 5!ways. Similarly When W and R are the first and last letters of the words then the remaining letters can be arrange in 5! ways.

Thus the total number of permutations = 2 x 5!  = 2 x 120 = 240

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