Question

Out of 320 families with 5 children each, what percentage would be expected to have 

a.) 2 boys and 2 girls and
b.) At least one boy ?

Answer 1

2      at least one boy
total favourable outcome  1595
total possible outcome are 1600
so
probability=1595/1600
                =99.68%
1  2 boys and 2 girls
total favourable outcome  1580
total possible outcome  1600
s0 
probability=1580/1600
                =98.75%