Question: Let N denote the number of children in a randomly picked family. Suppose N has geometric distribution:
P(N = n ) = (1/3) (2/3)n-1 (n = 1, 2, 3, . .)
And suppose each child is equally likely to be male or female. Let X be the number of male children and Y the number of female children, in a randomly picked family:
a) Find the joint distribution of (X, Y).
b) Given Y = 0, what is the most likely value of X?
c) What is the conditional expectation of X given Y = 0?