A train must follow the same route with the same time scheduling in every day. The departure time from a certain station is scheduled to be 12:00 am. However, the train may depart from the station some time earlier or later. The standard deviation is known to be 5.22 minutes. Suppose the departure times of the train are recorded for 15 days. (a) (2 points) Which value the corresponding x distribution would take if the sample standard deviation is computed 5.47? (b) (3 points) What would be the probability that the sample standard deviation is greater than 5.47?