A student who is trying to write a paper for a course has a choice of two topics, A and B. If topic A is chosen, the student will order two books through interlibrary loan, whereas if topic B is chosen, the student will order four books. The student believes that a good paper necessitates receiving and using at least half the books ordered for either topic chosen. If the probability that a book ordered through interlibrary loan actually arrives on time is 0.9 and books arrive independently of one another, which topic should the student choose to maximize the probability of writing a good paper?
What if the arrival probability is only 0.5 instead of 0.9?