Chapter 9.4, Problem 18STP

To determine

To determine the price of $21$ cookies.

Answer to Problem 18STP

The price of $21$ cookies is $5.25\text{ dollars}$

Explanation of Solution

Given information:

In the Graph there are three points $(2,0.5),(6,1.5)$ and $(8,2.0)$

  

The price of $21$ cookies

By the Rule of Constant Proportion:

1^st Point = $\frac{0.5}{2}=0.25$

2^nd Point= $\frac{1.5}{6}=0.25$

3^rd Point= $\frac{2.0}{8}=0.25$

So, Cost of $21$ cookies,

  $\begin{array}{l}21\times 0.25\\ =5.25\text{ dollars}\end{array}$