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 Quantitative Aptitude - Arithmetic Ability Questions

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Q:

Two trains 140 m and 160 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time (in seconds) which they take to cross each other, is:

A) 9 B) 9.6
C) 10 D) 10.8
 
Answer & Explanation Answer: D) 10.8

Explanation:

Relative speed = (60 + 40) km/hr =[ 100 x ( 5 / 18 ) ]m/sec = ( 250 /9 ) m/sec.
Distance covered in crossing each other = (140 + 160) m = 300 m.
Required time = [ 300 x ( 9/250 ) ] sec = ( 54/ 5 )sec = 10.8 sec.

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Filed Under: Problems on Trains

25 24978
Q:

A train speeds past a pole in 15 seconds and a platform 100 m long in 25 seconds. Its length is:

A) 50 m B) 150 m
C) 200 m D) data inadequate
 
Answer & Explanation Answer: B) 150 m

Explanation:

Let the length of the train be x metres and its speed be y m/sec.
Then, (x/y)= 15   y =(x/15)

 

(x+100)/25 = x/15

 

=> 15(x + 100) = 25x

 

=> 15x + 1500 = 25x

 

=> 1500 = 10x

 

=> x = 150 m.

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Filed Under: Problems on Trains

39 24976
Q:

In the 75 litres of mixture of milk and water, the ratio of milk and water is 4:1. The quantity of water required to make the ratio of milk and water 3:1 is 

A) 1 litre B) 3 litres
C) 4 litres D) 5 litres
 
Answer & Explanation Answer: D) 5 litres

Explanation:

Total quantity of mixture = 75 litre

Milk  :  Water  =  4  :  1   

            

                   3       :       1

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Filed Under: Alligation or Mixture

50 24954
Q:

Find the volume (in cm3) of a hemisphere of diameter 7 cm.

 

A) 77   B) 63  
C) 89.83   D) 54.13
 
Answer & Explanation Answer: C) 89.83  

Explanation:
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Filed Under: Volume and Surface Area
Exam Prep: Bank Exams

1 24952
Q:

A sum of Rs. 12,500 amounts to Rs. 15,500 in 4 years at the rate of simple interest. What is the rate of interest

A) 3% B) 4%
C) 5% D) 6%
 
Answer & Explanation Answer: D) 6%

Explanation:

S.I. = Rs. (15500 - 12500) = Rs. 3000.

 

Rate = 100*300012500*4 % = 6%

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Filed Under: Simple Interest
Exam Prep: GRE

20 24910
Q:

What is the measure of an exterior angle of a regular polygon of 6 sides?

 

A) 45 deg B) 60 deg
C) 40 deg D) 36 deg
 
Answer & Explanation Answer: B) 60 deg

Explanation:
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Filed Under: Area
Exam Prep: Bank Exams

0 24894
Q:

Out of 17 applicants 8 boys and 9 girls. Two persons are to be selected for the job. Find the probability that at least one of the selected persons will be a girl.

A) 19/34 B) 5/4
C) 20/34 D) 25/34
 
Answer & Explanation Answer: D) 25/34

Explanation:

The events of selection of two person is redefined as first is a girl and second is a boy or first is boy and second is a girl or first is a girl and second is a girl.

So the required probability:
=817*916+917*816+817*716

 

= 934+934+734
= 2534

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Filed Under: Probability

21 24846
Q:

In a two-digit number, if it is known that its unit's digit exceeds its ten's digit by 2 and that the product of the given number and the sum of its digits is equal to 144, then the number is :

A) 12 B) 24
C) 36 D) 48
 
Answer & Explanation Answer: B) 24

Explanation:

Let the ten's digit be x.

 

Then, unit's digit = x + 2.

 

Number = 10x + (x + 2) = 11x + 2

 

Sum of digits = x + (x + 2) = 2x + 2.

 

(11x + 2) (2x + 2) = 144

=> 22x^2+26x-140=0

 

=> (x - 2)(11x + 35) = 0

 

=> x = 2

 

Hence, Required Number = 11x + 2 = 24

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Filed Under: Problems on Numbers

28 24753