$*9\mathrm{.}18.$ Refer to Job proficiency Problems $9\mathrm{.}10$ and $9\mathrm{.}11$

a$.$ Using forward stepwise regression, find the best subset of predictor variables to predict job proficiency. Use $$ limits of $\mathrm{.}05$ and $\mathrm{.}10$ for adding or deleting a variable, respectively.

b$.$ How does the best subset according to forward stepwise regression compare with the best subset according to the $R_{a,p}^2$ criterion obtained in Problem $9\mathrm{.}11$a$?$