To calculate the percentage of error, you can use the following formula:
\[ \text{Percentage of Error} = \left( \frac{|\text{Estimated Value} - \text{Actual Value}|}{\text{Actual Value}} \right) \times 100 \]
In this case:
- Estimated Value = 18 ft
- Actual Value = 15 ft
Now, plug the values into the formula:
\[ \text{Percentage of Error} = \left( \frac{|18 - 15|}{15} \right) \times 100 \]
Calculate the absolute error:
\[ |18 - 15| = 3 \]
Now substitute this value back into the formula:
\[ \text{Percentage of Error} = \left( \frac{3}{15} \right) \times 100 \]
Calculate the fraction:
\[ \frac{3}{15} = 0.2 \]
Now multiply by 100 to get the percentage:
\[ 0.2 \times 100 = 20 \]
Therefore, Jill's percentage of error is 20.0%.