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

Correct Answer: Option D

Age of new boy = (Age of moved girl) – (Number of family members × Decreased in average)

= 24 – 24×4/12

= 24 – 8

= 16 years.