Ari had a college graduation party. She invited and predicted that 100 people would attend. 80 out of the 100 invited attended. Calculate the percent error in her prediction. Round to the nearest hundredth.
The percent error can be calculated using the formula:
\[ \text{Percent Error} = \left| \frac{\text{Predicted Value} - \text{Actual Value}}{\text{Actual Value}} \right| \times 100\% \]
Here, Ari predicted that 100 people would attend but the actual number of attendees was 80.
Plugging in the values:
\[ \text{Percent Error} = \left| \frac{100 - 80}{80} \right| \times 100\% \]
\[ \text{Percent Error} = \left| \frac{20}{80} \right| \times 100\% \]
\[ \text{Percent Error} = \left| 0.25 \right| \times 100\% \]
\[ \text{Percent Error} = 25\% \]
Therefore, the percent error in her prediction was 25%.