Using the California School Data Set from Your Textbook, You $\widehat {\text { TestScr }}$

Using the California School data set from your textbook, you run the following regression: $\widehat {\text { TestScr }}$ = 698.9 - 2.28 STR
n = 420, SER = 9.4
_{where TestScore is the average test score in the district and STR is the student-teacher ratio. The sample standard deviation of test scores is 19.05, and the sample standard deviation of the student teacher ratio is 1.89.
a.}
Find the regression R² and the correlation coefficient between test scores and the student teacher ratio.
b.
Find the homoskedasticity-only standard error of the slope.