Consider the regression model fit to the arsenic data in Exercise 12-12.

Use arsenic in nails as the response and age, drink use, and cook use as the regressors.

(a) Calculate 99% confidence intervals on each regression coefficient.

(b) Calculate a 99% confidence interval on mean arsenic concentration in nails when drink and cook

(c) Calculate a prediction interval on arsenic concentration in nails for the same values of the regressors used in the previous part.