63. Airline travelers should be ready to be more flexible as airlines once again cancel thousands of flights this summer. The Coalition for Airline Passengers Rights, Health, and Safety averages 400 calls a day to help stranded travelers deal with airlines (http://seattlepi.com, July 10, 2008). Suppose the hotline is staffed for 16 hours a day. a. Calculate the average number of calls in a one-hour interval; 30-minute interval; 15-minute interval. b. What is the probability of exactly six calls in a 15-minute interval? c. What is the probability of no calls in a 15-minute interval? d. What is the probability of at least two calls in a 15-minute interval