Question

In a class there are 72 boys whose average age is decreased by 2.5 months, when 1 boy aged 30 years is replaced by a new boy. Find the age of the new boy.

Answer 1

Effect on total age of the class=72×2.5=180 month

Or 15 years decreases so the ageof new boy will be 30-15=15 years

Answer 2

The average age of the mother and her six children is 12 years which is reduced by 5 years if the age of the mother is excluded. H