87. Suppose that p  P(male birth)  .5. A couple wishes to have exactly two female children in their family. They will have children until this condition is ful lled.

a. What is the probability that the family has x male children?

b. What is the probability that the family has four children?

c. What is the probability that the family has at most four children?

d. How many male children would you expect this family to have? How many children would you expect this family to have?