Supplier on-time delivery performance is critical to enabling the buyer's organization to meet its customer service commitments. Therefore, monitoring supplier delivery times is critical. Based on a great deal of historical data, a manufacturer of personal computers finds for one of its just-in-time suppliers that the delivery times are well approximated by the normal distribution with mean 47.7 minutes and standard deviation 13.9 minutes. A random sample of 6 deliveries is selected. a) What is the probability that a particular delivery will arrive in less than one hour? Round your answer to four decimal places. b) What is the probability that the mean time of 6 deliveries will exceed one hour? Round your answer to four decimal places. c) Between what two times do the middle 60% of the average delivery times fall? and Round your answers to two decimal places. d) What is the probability that, in a random sample of 6 deliveries, more than three will arrive in less than an hour? Round your answer to four decimal places.