AutoReports is a consumer magazine that reports on the cost of maintaining various types of automobiles. The magazine collected the data found in the file Dat9-16.xls on your data disk describing the annual maintenance cost of a certain type of luxury imported automobile along with the age of the car (in years).

a. Prepare a scatter plot of these data.

b. Let Y = Maintenance Cost and X = Age. Fit the following regression model to the data:

Ŷi = b0 + b1X1i

Plot the maintenance costs that are estimated by this model along with the actual costs in the sample. How well does this model fit the data?

c. Fit the following regression model to the data:

Ŷi = b0 + b1X1i + b2X2i

Where X2i = X21i. Plot the maintenance costs that are estimated by this model along with the actual costs in the sample. How well does this model fit the data?

d. Fit the following regression model to this data:

Ŷi = b0 + b1X1i + b2X2i + b3X3i

Where X2i = X21i and X3i = X31i. Plot the maintenance costs that are estimated by this model along with the actual costs in the sample. How well does this model fit the data?