Question

At Joe's Pizza a 16 inch diameter pizza and a 12-inch-diameter pizza cost the same per square inch of top surface area. If the cost of a large pizza is 9.60, what is the cost, in dollars, of the small pizza?

Answer 1

5.4

Explanation:

Surface area of the large 16 in diameter pizza is

`A = \pi(d/2)^2 = \pi8^2 = 64\pi`

Cost per unit surface area is

`c = (9.6)/(64\pi) = (0.15)/(\pi)`

Surface area of the small 12-in diameter pizza is

`a = \pi(12/2)^2 = \pi6^2 = 36\pi`

So the total cost for that much surface area of pizza is

`ac = 36\pi*(0.15)/(\pi) = 5.4`