If Susan bought nine gallons of gasoline at $1.50 per gallon, the car wash cost $1, but if she bought 10 gallons of gasoline, the car wash was free. Given that Susan is going to get the car wash, the marginal cost of the tenth gallon of gasoline is

Question

Quizplus · Accepted Answer

The cost of the first 9 gallons of gasoline is ($1.50 per gallon x 9 gallons) = $13.50.

If Susan buys the 10th gallon, the total cost of gasoline would be ($1.50 per gallon x 10 gallons) = $15.

Since the car wash is free with the purchase of 10 gallons of gasoline, the marginal cost of the 10th gallon is the difference between buying 9 gallons and 10 gallons, which is $15 - $13.50 = $.50.

Therefore, the answer is B.

If Susan Bought Nine Gallons of Gasoline at $1