1. Time spent serving a customer at a cafe is normally distributed, with = 7 minutes and 1.8 minutes. (a) If you select a random sample of duration serving twenty five (25) customers, determine the probability that the sample mean is between 6.8 and 7.2 minutes. (b) [9 marks] If you select a random sample of 144 customers, determine the probability that the sample mean is between 6.8 and 7.2 minutes. [6 marks] (c) Explain the difference in the results of (i) and (ii). [6 marks]