Refer to Exercise 88. a. Construct and interpret a 90% confidence interval for the true mean difference.

Question:

Refer to Exercise 88.

a. Construct and interpret a 90% confidence interval for the true mean difference. If you already defined parameters and checked conditions in Exercise 88, you don’t need to do them again here.

b. Explain how the confidence interval provides more information than the test in Exercise 88.

Exercise 88.

Do people behave differently on Friday the 13th? Researchers collected data on the number of shoppers at a random sample of 45 grocery stores on Friday the 6th and Friday the 13th in the same month. Then they calculated the difference (subtracting in the order 6th minus 13th) in the number of shoppers at each store on these 2 days. The mean difference is and the standard deviation of the differences is 178.0.