Chapter 7.3, Problem 38CCR

To determine

Find the number of cups of slat she should use.

Answer to Problem 38CCR

For 9 cups of flour she needs to use 6.25 cups of salt.

Explanation of Solution

Given:

Tara is making salt dough for a craft project. She uses 3 cups of salt to 4 cups of flour to make the dough. If she uses 9 cups of flour, how many cups of salt should she use?

Concept Used:

She uses 3 cups of salt to 4 cups of flour to make the dough. Ratio of Slat to flour is 3 : 4.

Let the number of cups of slat she will use for 9 cups of flour.

Now set a proportion: $\frac{\text{Salt}}{\text{Flour}}=\frac{3}{4}=\frac{x}{9}$

Calculation:

Proportion: $\frac{\text{Salt}}{\text{Flour}}=\frac{3}{4}=\frac{x}{9}$

  $\begin{array}{l}\frac{3}{4}=\frac{x}{9}[\text{use}\text{cross}\text{multiplication}]\\ 4x=27\\ \frac{4x}{4}=\frac{27}{4}[\text{divide}\text{each}\text{side}\text{by}\text{4}]\\ x=6.25\end{array}$

For 9 cups of flour she needs to use 6.25 cups of salt.

Thus, For 9 cups of flour she needs to use 6.25 cups of salt.