Chapter 2 - Solving Equations - 2-10 Change Expressed as a Percent - Got It? - Page 146: 3

$15.79\%$

Using $$ \text{percent error}=\frac{|\text{estimated value}-\text{actual value}|}{\text{actual value}} ,$$ then $$\begin{aligned} \text{percent error}&=\frac{|5.5-4.75|}{4.75} \\&= \frac{0.75}{4.75} \\&\approx 0.1579 \\&\approx 15.79\% .\end{aligned} $$ Hence, the percent error in the estimation is approximately $15.79\%$.