Suppose that the purchase price of automobiles varies with weight according to the formula that weight in lbf × $8.00, and gas mileage varies according to mpg = (84,500 mile-lbf/gal)/W – 3.0 miles/gal. Graph the cost per mile of operating a car as a function of the car’s weight, in increments of 500. lbf from 2000. lbf to 5000. lbf. (Partial A: 29 cents/mile for 2000. lbf car and 76 cents/mile for 5000. lbf car)

The fixed costs per year of operating an automobile is approximately 20.% of the initial price of the car. Thus, the operating cost/mile = 0.20/yr × (purchase price of automobile)/(miles driven per year) þ (price of gasoline/gallon) × (gallons used per mile). In the exercises that follow, assume that the automobile is driven 2.0 × 10⁴ miles per year. Assume gasoline costs $5.00/gallon.