Chapter 7, Problem 39CR

To determine

To Find: The number whose certain percentage is a given number, using the percent equation.

Answer to Problem 39CR

  $2.56$ is $8\%$ of $32$

Explanation of Solution

Given Information: The number is $2.56$ and the percent is $8\%$ .

Method: The percent equation is $a=p\%\cdot b$ and it represents the sentence “ $a$ is $p\%$ of $b$ ”.

• Put the given values of $p$ and $a$ in the equation.
• Write $p\%$ as a decimal and then algebraically solve for $b$

Put the given values in the percent equation to write

  $2.56 = 8\%\cdot b$

To write $8\%$ as a decimal, remove the $\%$ sign and move the decimal point $2$ places to the left. So $8\%$ written as a decimal is $0.08$

Therefore

  $2.56 = 0.08\times b$

Divide the equation by $0.08$ to get

  $b=\frac{2.56}{0.08}=32$

Therefore, the number whose $8\%$ is $2.56$ is $32$