10 years ago, the average age of a family of 4 members was 24 years. Two children having been born (with age diference of 2 years), the present average age of the family is the same. The present age of the youngest child is 

A -1

B 9

C 12

D 3

Solution

Correct Answer: Option D

Total age of 4 members, 10 years ago = (24 x 4) years = 96 years.

 

Total age of 4 members now = [96 + (10 x 4)] years = 136 years.

 

Total age of 6 members now = (24 x 6) years = 144 years.

 

Sum of the ages of 2 children = (144 - 136) years = 8 years.

 

Let the age of the younger child be x years.

 

Then, age of the elder child = (x+2) years.

 

So, x+(x+2) =8 <=> x=3

 

Age of younger child  =  3 years.

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