Question

In a joint family, there are 24 members whose age is decreased by 4 months, when one girl aged 24 years is replaced by a new boy. Find the age of the new boy ?

Answer 1

In a joint family, there are 24 members whose age is decreased by 4 months, when one girl aged 24 years is replaced by a new boy. Find the age of the new boy ?
A) 18 years
B) 12 years
C) 15 years
D) 16 years

Answer:

Let age of the new boy was X.

Age decreased = 4 months = 4/12 = 1/3 years

Now, we have formula for this type of questions,

Number of members in the Group × age decreased = difference in ages of boy in and boy out.

=>24 × (1/3) = 24 -X

=>8 = 24 - X

=>X = 24 -8

=>X = 16 years.

Answer 2

Let age of the new boy was X.

Age decreased = 4 months = 4/12 = 1/3 years

Now, we have formula for this type of questions,

Number of members in the Group * age decreased = difference in ages of boy in and boy out.

24 * (1/3) = 20 -X

X = 12 years.

 

Thought process method:

Total age decreased = 4 *24 = 96 months = 8 years.

It means the difference of the ages between boy in and out would be = 20 - 8 = 12 years.