Consider human subships with 4 children and assume that each

Consider human subships with 4 children and assume that each birth is equally likely to result in a boy (B) or a girl (G)?

What fraction is expected to have two girls and 2 boys ?

Solution

Consider human subships with 4 children and assume that each birth is equally likely to result in a boy (B) or a girl (G)?

every issue --------probability of boy (B)=1/2

every issue --------probability of girl (G)=1/2
What fraction is expected to have two girls and 2 boys ?

(a+b)^4= a^4 +4a^3b+6a ^2 b^2 +4ab^3+b^4

= 6 x ( 1/2) ^ 2 x ( 1/2) ^ 2

=0.375