The test scores on a 100-point test were recorded for 20 students: 71 93 91 86 7573 86 82 76 5784 89 67 62 7277 68 65 75 84 a.

The test scores on a 100-point test were recorded for 20 students:

71 93 91 86 7573 86 82 76 5784 89 67 62 7277 68 65 75 84

a. Can you reasonably assume that these test scores have been selected from a normal population? Use a stem and leaf plot to justify your answer.

b. Do the sample data suggest that the average test score is more than 75? Use α = 0.05.

c. If these students can be considered a random sample from the population of all students,find a 95% confidence interval for the average test score in the population.