An engineer wants to develop a model to describe the gas mileage of a sport utility vehicle. He collects the data presented in Table 10. The final drive ratio is the ratio of the gear set that is farthest from the engine. A higher ratio generally means better acceleration and pulling power. Use the forward selection procedure to find the best model to describe miles per gallon. Use a level of significance of \(\alpha=0.05\) as the criteria for an explanatory variable to enter the model.

Approach We will use Minitab to find the best model.

Table 10 Sport Utility Vehicle Curb Weight (pounds) Engine Size (liters) Cylinders Final Drive Ratio (:1) Ground Clearance Miles per (inches) Gallon Mercedes-Benz G500 5510 5.0 8 4.38 8.3 13 Jeep Wrangler X 3760 3.8 6 3.21 8.8 16 Mitsubishi Endeavor LS 2WD 3902 3.8 6 4.01 8.3 18 Toyota Land Cruiser 5690 5.7 8 3.91 8.9 15 Kia Sorento 4 2 4068 3.3 6 3.33 8.2 18 Jeep Commander Sport 4x2 4649 4.7 8 3.73 8.6 15 Dodge Durango SLT 4x2 4709 4.7 8 3.55 8.7 15 Lincoln Navigator 4 2 5555 5.4 8 3.73 9.2 15 Chevrolet Tahoe LS 2WD 5265 4.8 8 3.23 9.1 16 Ford Escape FWD 3387 3.0 6 2.93 8.5 20 Ford Expedition XLT 5578 5.4 8 3.31 8.7 14. Buick Enclave CX FWD 4780 3.6 6 3.16 8.4 19 Cadillac Escalade 2WD 5459 6.2 8 3.42 9.0 14 Hummer H3 SUV 4689 3.7 5 4.56 9.1 15 Saab 9-7X 4720 4.2 6 3.73 7.7 16