Consider the NFL data in Exercise 12-17.

(a) Find 95% confidence intervals on the regression coefficients.

(b) What is the estimated standard error of when the percentage of completions is 60%, the percentage of TDs is 4%, and the percentage of interceptions is 3%.

(c) Find a 95% confidence interval on the mean rating when the percentage of completions is 60%, the percentage of TDs is 4%, and the percentage of interceptions is 3%.