Question

A 6 inch personal pizza has 640 calories, with 240 of those from fat. A 12 inch pizza is cutinto 8 slices. Estimate the number of calories in one slice of a 12 inch pizza. Must use Pi*r2 proportions to solve.

Answer 1

Given:

Number calories in a 6-inch pizza = 640 calories

For the pizza of 6 inch

$A=\pi(3)^2=9\pi$

For the pizza of 12 inch

$A=\pi(6)^2=36\pi$

Number calories in a 6-inch pizza = 640 calories, therefore:

$\frac{A_{6\text{ inch}}}{A_{12\text{ inch}}}=\frac{640}{x}$

Substitute:

$\begin{gathered} \frac{9\pi}{36\pi}=\frac{640}{x} \\ Simplify \\ \frac{1}{4}=\frac{640}{x} \end{gathered}$

And solve for x:

$\begin{gathered} 1\cdot x=4\cdot640 \\ x=2560 \end{gathered}$

Now, Estimate the number of calories in one slice of a 12 inch pizza:

$\frac{2560}{8}=320$

Answer: 320 calories