You may need to use the appropriate appendix table or technology to answer this question. During the period of time that a local university takes phone-in registrations, calls come in at the rate of one every four minutes. (a) What is the expected number of calls in one hour? (b) What is the probability of two calls in five minutes? (Round your answer to four decimal places.) (c) What is the probability of no calls in a five-minute period? (Round your answer to four decimal places.)