Use the data set GPA$1.$DTA for this question. $(40$pts$)$

a$.$ Use OLS to estimate a model relating colGPA to hsGPA, ACT, skipped, and PC$.$

Obtain the OLS residuals.

b$.$ Compute the special case of the White test for heteroskedasticity. In the

regression of $$

$$ on $$

$,$

$,$ obtain the fitted values, using predict

command. Report your findings.

c$.$ Is heteroskedasticity present? Show evidence