Consider the following data from Exercise 12.13 on page 472. 1. Estimate using multiple regression of y on x and x . 2 1

Consider the following data from Exercise 12.13 on page 472.

1. Estimate σ using multiple regression of y on x and x .

2 1 2 2

1 2 3 4 2

1 2 2. Compute predicted values, a 95% confidence interval for mean wear, and a 95% prediction interval for observed wear if x = 20 and x = 1000.