Which one of the following is a better​ buy: a large pizza with a 12

​-inch
diameter for $ 15.00

or a medium pizza with a 6
​-inch
diameter for $ 5.00
​?

1 answer

To compare the two options, we need to calculate the price per square inch of pizza.

For the large pizza:

- Radius is half the diameter, so the radius of this pizza is 6 inches.
- Area of a circle = πr², so the area of this pizza is π(6)² = 36π square inches.
- Price per square inch = $15.00 ÷ 36π ≈ $0.13/square inch.

For the medium pizza:

- Radius is half the diameter, so the radius of this pizza is 3 inches.
- Area of a circle = πr², so the area of this pizza is π(3)² = 9π square inches.
- Price per square inch = $5.00 ÷ 9π ≈ $0.18/square inch.

Therefore, the large pizza is the better buy, since it has a lower price per square inch of pizza.