Question

A professor of a law school observes that only 25% of students who get admitted to the freshman class reach fourth year. assuming that this is correct, among 15 randomly selected first year students,
a. find the probability that exactly 8 will reach fourth year.
b. find the probability that at most 7 will reach fourth year.
c. find the probability that between 7 and 10, inclusive will reach fourth year.
d. find the expected number of students who will reach fourth year for the next 25 students.