Prove that the derivation of the covariance of  and in (A.10) of Appendix A. For the 18-hole courses in file golfsrs.dat, plot the weekend 18-hole greens fee vs. the backtee yardage. Estimate the regression parameters for predicting weekend greens fees from backtee yardage. Is there a strong relationship between the two variables? Use regression estimation to estimate the weekend 18-hole greens fee with its standard error.