Probability question

Question

Assume that each child who is born is equally likely to be a boy or a girl. If a family
has two children, what is the (conditional) probability that both are girls given that at
least one is a girl?

Answer 1

P(BB) = P(BG) = P(GB) = P(GG) = ¼

 

P(G|G) = P(GG) / P(one or more G) = ¼ ÷ ¾ = 1/3.