The manager at an automobile dealership would like to estimate the average satisfaction score from the 915 customers who purchased a car or truck last year. The company goal is to achieve an average satisfaction score of at least 80 on a scale of 0– 100. A random sample of 80 customers had an average satisfaction score of 82.7 and a sample standard deviation of 6.7.
a. Construct a 95% confidence interval to estimate the actual average satisfaction score from last year’s customers.
b. Based on this sample, can the manager conclude that the company goal has been achieved?
c. Verify your results with PHStat.