Suppose that P(male birth) = 0.5. A couple wishes to have exactly 2 female children in their family. They will have children until this condition is fulfilled.

a) What is the probability that the family has x male children? (ans: (x + 1) * 0.5^(x+2))

b) What is the probability that the family has four children? (ans: .0.188)

c) What is the probability that the family has at most four children? (ans: 0.688)

d) How many male children would you expect this family to have? How many children would you expect this family to have? (Ans:expected 2 male children , 4 children in total)