A national chain of fast-food restaurants has a 1-800 customer service line to deal with customer complaints. The number of calls received in any given hour is thought to follow a Poisson distribution. Over the past year, the customer service line has received an average of 25.4 calls per hour. (a) What is the probability that 10 or fewer calls will be received in a given hour? (b) What is the probability that 15 or more calls will be received in a given hour? (c) If any one operator is able to answer 6 calls per hour, how many operators should the customer service line employ in order to be 95% confident that the operators will be able to handle all of the calls received in a given hour? (d) If, in a given hour, the customer service line received 60 calls, what would you conclude?