In Problem 13.7 on page 531, you used the number of customers to predict the waiting time on the checkout line. The data are stored in Supermarket. Use the results of that problem.
a. At the 0.05 level of significance, is there evidence of a linear relationship between the number of customers and the waiting time on the checkout line?
b. Construct a 95% confidence interval estimate of the population slope, β1.