13.29 The data file Electric Cars contains observations on the starting price, driving range, battery capacity, and number of seats for electric cars available in the European car market. PanCars, an importer, wishes to understand the relationship among the starting price (the price of the most basic version of the car, excluding optional upgrades), the driving range (in kilometers), and the number of seats.

a. Estimate the multiple regression model of starting price on the driving range and the number of seats.

b. Graphically check for heteroscedasticity.

c. Use a formal hypothesis test to check for heteroscedasticity.

d. If you establish that there is heteroscedasticity in (b)

or (c), perform another regression that corrects for heteroscedasticity.