A statistics instructor is interested in the ability of students to assess the difficulty of a test they have taken. This test was taken by a large group of students, and the average score was 78.5. A random sample of eight students was asked to predict this average score. Their predictions were: 72 83 78 65 69 77 81 71 Assuming a normal distribution, test the null hypothesis that the population mean predic tion would be 78.5. Use a two-sided alternative and a 10% significance level.