It is estimated that 55% of the freshmen entering a particular college

It is estimated that 55% of the freshmen entering a particular college will graduate from that college in four years.
(a) What probability model should be used and why?
(b) For a random sample of 5 entering freshmen, what is the probability that exactly 3 will graduate in four years.
(c) For a random sample of 5 entering freshmen, what is the probability that a majority will graduate in four years.
(d) 80 entering freshmen are chosen at random. Find the mean and standard deviation of these 80 that will graduate in four years.