Question

A board is cut so that its length is changed from 8 feet to 6.5 feet. What is the percent of change in length? Round your answer to the nearest tenth, if necessary. a. –18.8% c. 18.8% b. –23.1% d. 81.2%

Answer 1

it went from 8 to 6.5, namely 8 - 6.5 = 1.5.

if we take the 8 to be the 100%, what is 1.5 off of it in percentage?

$\bf \begin{array}{ccll}amount&\%\\\cline{1-2}8&100\\1.5&x\end{array}\implies \cfrac{8}{1.5}=\cfrac{100}{x}\implies x=\cfrac{1.5\cdot 100}{8}\implies x=18.75$

well, we can round that up to 18.8%, however since it's a subtraction from the board, we can say is -18.8%, a negative percent, because is a percent that was taken out of it.