Use the model you selected in Exercise 13.79 to complete the following.
a. Estimate the average level of sulfur dioxide content of the air in a city having the following values for the six explanatory variables:
x1 = 60 x2 = 150 x3 = 600 x4 = 10 x5 = 40 x6 = 100
b. Place a 95% confidence interval on your estimated sulfur dioxide level.
c. List any major limitations in your estimation of this mean.