Suppose you have 15 identical dollar bills to give to your friends
Adam, Beth and Charlie. You give all 15 dollar bills away by
randomly selecting a person for each dollar. Each person is equally
likely to recieve a dollar for each dollar. (a) What is the
probability that Adam gets exactly 4 dollars? (b) If you know that
each person recieved at least one dollar, what is the probability
that Adam gets exactly 4 dollars? (c) What is the expected number
of dollars that Adam gets? (d) If you know that each person
recieved at least one dollar, what is the expected number of
dollars that Adam gets?