Chapter 8.3, Problem 14E

a.

To determine

Construct a multiple linear regression model $y\text{=}{\beta }_0+{\beta }_1{x}_1\text{+}{\beta }_2{x}_2+\epsilon$ for the given data.

Plot the residuals versus fitted line plot for the obtained model.

Check whether the model is appropriate.

b.

To determine

Construct a multiple linear regression model $\ln y\text{=}{\beta }_0+{\beta }_1\ln x_1\text{+}{\beta }_2\ln x_2+\epsilon$ for the given data.

Plot the residuals versus fitted line plot for the obtained model.

Check whether the model is appropriate.

c.

To determine

Find the predicted value of y when $x_1=50$ and $x_2=100$ using the more appropriate model.

d.

To determine

Explain whether the model used in part (c) is improved by including an interaction term.