In Problem 13.7 on page 470, you used the total number of staff present and remote hours to predict standby hours (stored in Standby). Using the results from that problem,

a. Construct a 95% confidence interval estimate of the population slope between standby hours and total number of staff present.

b. At the 0.05 level of significance, determine whether each independent variable makes a significant contribution to the regression model. On the basis of these results, indicate the independent variables to include in this model.