Exercise 35 of Section 3.5 gave data on x1 wire feed rate, x2 welding speed, and y deposition rate of a welding process. Minitab output from fitting the multiple regression model with x1 and x2 as predictors is given here.
a. Carry out the model utility test.
b. Calculate and interpret a 95% confidence interval for 2, the population regression coefficient of x2.
c. When x1 11.5 and x2 40, the estimated standard deviation of is s .02438. Calculate a 95% confidence interval for true average deposition rate for the given values of x1 and x2.
d. Calculate a 95% prediction interval for the deposition rate resulting from a single experimental run with x1 11.5 and x2 40.
Fill in all the columns in the design matrix for the 252 design of Example 10.12.