If we were to double the price of the automobile in exercise 18, what would its gas mileage have to be in order to cost the same to operate per mile as the automobile in exercise 18?

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.

Exercise 18

Estimate the operating cost per mile of an automobile with a price of $15,000 that gets 30.0 miles per gallon. (A: $0.32/mile)