1. The average time required for people to complete the payment process at a market has been 40 minutes. A market administrator is trying a new procedure. Under this procedure, the payment times of 20 randomly selected people are recorded, resulting in a sample means of 37.2 minutes and a sample standard deviation of 4.5 minutes. It can be safely assumed that the distribution of payment times is reasonably close to a normal distribution.

a. Assuming there has been no improvement in the average time with the new procedure, determine the probability that the mean time for 20 people would be 37.2 minutes or less.

b. In view of your answer to part (a), is there good reason for the market administrator to believe that the new procedure is an improvement? Explain.

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a To determine the probability that the mean time for 20 people would be 372 minutes or less we can ... View the full answer