A warehouse manager is interested in the possible improvements to labor efficiency if air-conditioning is installed in the warehouse. The data set given in DS 12.2.2 is collected which shows the times taken to unload a fully laden truck at various temperature levels.
(a) Fit a linear regression model with time as the dependent variable and temperature as the explanatory variable.
(b) What is the estimate of the error variance?
(c) Does the model suggest that the unloading time increases with temperature?
(d) What is the predicted unloading time when the temperature is 72° F?
(This problem is continued in Problems 12.3.4, 12.6.6, 12.7.2, and 12.9.4.)