Spam e-mail has become a serious and costly nuisance. An office manager believes that the average amount of time spent by office workers reading and deleting spam exceeds 24 minutes per day. To test this belief, he takes a random sample of 18

workers and measures the amount of time each spends reading and deleting spam. The results are listed below. If the population of times is normally distributed with a standard deviation of 10 minutes, can the manager infer at the 1% significance level that he is correct?

35 48 29 44 17 21 32 28 34

23 13 9 11 30 42 37 43 48

if the population of times is normally distributed with a standard deviation of 10 minutes, can the managerinfer at the 1% significance level that he is correct?