In Problem 12.7 on page 424, you used the plate gap in the bag sealing equipment to predict the tear rating of a bag of coffee. The data are stored in Starbucks. Use the results of that problem.

a. At the 0.05 level of significance, is there evidence of a linear relationship between the plate gap of the bag sealing machine and the tear rating of a bag of coffee?

b. Construct a 95% confidence interval estimate of the population slope, β₁.