Chapter 6, Problem 7CR

To determine

To find the number of classical CD’s Monique has.

Answer to Problem 7CR

  $36$

Explanation of Solution

Given:

  $30\%$ of $120$ CD’s are classical

Concept used:

To translate a phrase of the form “whatis $A$ percent of $B$ ?” to an equation. First, assume that the numberis $x$ . Then, read the statement is $A\%$ of In “ $A\%$ of the word “of” represents “multiplication”. So, the given statement can be translated in to an equation as follows:

  $\begin{array}{ccccc}x& \text{is}& A\%& \text{of}& B\\ \downarrow & \downarrow & \downarrow & \downarrow & \downarrow \\ x& =& \frac{A}{100}& ·& B\end{array}$

So, the equation becomes $x=\frac{A}{100}·B$ .

Calculation:

Using the concept, the given statement can be translated into an equation as

  $x=30\cdot \frac{1}{100}\cdot 120$ .

Now, solve the equation as follows:

  $\begin{array}{c}x=30\cdot \frac{1}{100}\cdot 120\\ x=36\end{array}$

Therefore, number of classical CD’s is

  $x=36$

Conclusion:

The solution of the percent problem is $36$ .