Question

2 Years before,average age of 8 numbers of family was 20yr.if present average of family even on inclusion of 1 child,remains same.present age of child is?

Answer 1

The sum of their ages 2 years ago was 8*20 = 160

So, if the new child's age is x,

160 + 8*2 + x = 9*20
x = 4