Transportation Research, Inc., has asked you to prepare some multiple regression equations to estimate the effect of variables on fuel economy. The data for this study are contained in the data file Motors, and the dependent variable is miles per gallon-milpgal-as established by the Department of Transportation certification.
a. Prepare a regression equation that uses vehicle horsepower-horsepower-and vehicle weight- weight-as independent variables. Interpret the coefficients.
b. Prepare a second regression equation that adds the number of cylinders-cylinder-as an independent variable to the equation from part a. Interpret the coefficients.
c. Prepare a regression equation that uses number of cylinders and vehicle weight as independent variables. Interpret the coefficients and compare the results with those from parts a and b.
d. Prepare a regression equation that uses vehicle horsepower, vehicle weight, and price as predictor variables. Interpret the coefficients.
e. Write a short report that summarizes your results.