One family has 40% left-hand members in each generation. If 4 grandchildren are left-handed, how many grandchildren are there in all?

Question

 i just don't understand how to go about this question 

Answer 1

If there are 4 left handed grandchildren, and 40% of each generation is left handed, then, because the grandchildren are a generation (like the parents are a generation and the grandparents are a generation), then,

 

4 = 40% of x, with x being the number of individuals in a population.

 

4 = .4x

x = 10