Chapter 11.5, Problem 17WE

To determine

To Find: Which is the better buy?

Answer to Problem 17WE

  $15in$ pizza.

Explanation of Solution

Given: $10in$ pizza costing $\$5$ or $15in$ pizza costing $\$9$ .

For $10in$ pizza

  $\begin{array}{l}d=10\\ r=\frac{d}{2}=\frac{10}{2}=5\\ A=\pi r^2\\ $ A=3.14{(5)}^2$A=78.5i{n}^2\\ \text{unit cost=}\frac{5}{78.5}=\$0.0637\end{array}$

For $15in$ pizza.

  $\begin{array}{l}d=15\\ r=\frac{d}{2}=\frac{15}{2}=7.5\\ A=\pi r^2\\ $ A=3.14{(7.5)}^2$A=176.625i{n}^2\\ \text{unit cost=}\frac{9}{176.625}=\$0.0510\end{array}$

The unit cost of $15in$ is less.

Thus ‘

  $15in$ pizza is the better buy.