The manager of a large shopping mall in Knysna believes that visitors to the mall spend, on average, 85 minutes in the mall on any one occasion. To test this belief, the manager commissioned a study, which found that, from a random sample of 132 visitors to the mall, the average visiting time was 80.5 minutes. Assume a population standard deviation of 25 minutes and that visiting time is approximately normally distributed.
(a) Formulate the null and alternative hypothesis for this test situation.
(b) Which test statistic (z or t) is appropriate for this test? Why?
(c) Conduct a hypothesis test for a single mean at the 5% significance level to support or refute the manager's belief. What management conclusion would be drawn from the findings?
(d) Use Excel's NORMSDIST function to compute the p-value for the test.
(e) What statistical and management conclusion could be drawn from the p-value?