Quantitative Aptitude - Arithmetic Ability Questions

Q:

The average age of a group of 10 students is 15 years. When 5 more students join the group, the average age increase by 1 year. The average age of the new student is?

Answer

Total age of 10 students = 150 years


Total age of 15 students = 240 years


Total age of 5 new students = 240 - 150 = 90 years


 Average age of 5 new students = 90/5 = 18 years.

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Subject: Problems on Ages

5 6097
Q:

You drive to the store at 20 kmph and return by the same route at 30 kmph. Discounting the time spent at the store, what was your average speed ?

A) 25 kmph B) 24 kmph
C) 26 kmph D) 22 kmph
 
Answer & Explanation Answer: B) 24 kmph

Explanation:

Average speed=total distance/total time
Let distance to store be  K
then, total time =(K/20)+(K/30)=K/12
and, total time =(2K)
so average speed= 2K / (K/12) = 24kmph.

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Filed Under: Time and Distance
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3 6092
Q:

A wheel that has 6 cogs is meshed with a larger wheel of 14 cogs. When the smaller wheel has made 21 revolutions, then the number of revolutions made by the larger wheel is ?

A) 11 B) 7
C) 9 D) 13
 
Answer & Explanation Answer: C) 9

Explanation:

Here the number of cogs is inveresly proportional to number of revolutions

=> More cogs less revolution
=> 6 : 14 :: x : 21
=> (21x6)/14 = 9

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Filed Under: Ratios and Proportions
Exam Prep: AIEEE , Bank Exams , CAT , GATE
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6 6091
Q:

Application of Inverse Proportion

If 20 persons can do a piece of work in 7 days then calculate the number of persons require to complete the work in 28 days

Answer

Number of persons * days = work  


20 * 7 = 140 man- days 


 


Now,  x * 28  = 140 men- days


=> x =5         


Therefore in second case the required number of person is 5.


 


Second method:


Since work is constant, therefore  M1 x D1= M2 x D2


20 x 7 = M2 x 28


=> M2 = 5 


 

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Subject: Time and Work

5 6077
Q:

If log330 = 1a  and  log530=1b then the value of 3log302 is:

A) 3(1+a+b) B) 2(1-a-b)
C) 3(1-a-b) D) 3(1+a-b)
 
Answer & Explanation Answer: C) 3(1-a-b)

Explanation:
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Filed Under: Logarithms
Exam Prep: AIEEE , Bank Exams , CAT
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25 6066
Q:

A tank is filled in eight hours by three pipes K, L and M. Pipe K is twice as fast as pipe L, and L is twice as fast as M. How much time will pipe L alone take to fill the tank ?

A) 32 hrs B) 24 hrs
C) 28 hrs D) 26 hrs
 
Answer & Explanation Answer: C) 28 hrs

Explanation:

1/K + 1/L + 1/M = 1/8 (Given)
Also given that K = 2L and L = 2M
=> 1/2L + 1/L + 2/L = 1/8
=> (1 + 2 + 4)/2L = 1/8
=> 2L/7 = 8
=> L = 28 hours.

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Filed Under: Pipes and Cistern
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8 6064
Q:

The ratio between the number of sheep and the number of horses at the Stewar farm is 4 to 15. If each of horse is fed 110 ounces of horse food per day and the farm needs a total 13200 ounces of horse food per day. what is number sheep in the form ?

A) 32 B) 36
C) 44 D) 52
 
Answer & Explanation Answer: A) 32

Explanation:

Given ratio of number of sheep and horses = 4 : 15
Let number of sheep and horses are 4k and 15k
Number of horses = 13200/110 = 120
Now 15K = 120 and k = 8
Number of sheep = 4k = (4 x 8) = 32

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Filed Under: Ratios and Proportions
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8 6054
Q:

A certain sum of money is invested for one year at a certain rate of simple interest. If the rate of interest is 3% higher, then the invest earned will be 25% more than the interest earned earlier. What is the earlier rate of interest ?

A) 4% p.a. B) 6% p.a.
C) 8% p.a. D) 12% p.a.
 
Answer & Explanation Answer: D) 12% p.a.

Explanation:

If the interest earned is 25% more than the earlier interest then the rate of interest also should be 25% higher than the earlier rate.
Let the earlier rate of interest be x%.
Now it will be (x + 3)%
% increase = (x + 3) - x/x * 100 = 25
=> x = 12%

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Filed Under: Profit and Loss
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5 6052