Question

Find the percent of decrease from 85 inches to 39 inches. Round to the nearest tenth of a percent if necessary.

Answer 1

Since 85 inches represents the 100%, we can state the following rule of three:

$\begin{gathered} \text{ 85 inches ----- 100 \%} \\ \text{ 39 inches ----- x} \end{gathered}$

Then, by cross-multiplying these numbers, we have

$x\times\text{ 85 inches = (39 inches ) }\times\text{ (100\%)}$

So, x is given by

$\begin{gathered} x=\frac{\text{(39 inches ) }\times\text{ (100\%)}}{\text{ 85 inches}} \\ x=\text{ 45.88 \%} \end{gathered}$

Then, the percent of decrease will be

$100\text{ \% - 45.88 \% = 54.12 \%}$

and by rounding to the nearest tenth, the answer is 54.1 %