Certainly! Let's break down the process of calculating Teresa's percent error step by step.
1. Understanding Percent Error
Percent error is a way to express how much an estimated or measured value deviates from the actual value, relative to the actual value itself. It tells us how inaccurate an estimate is in terms of percentage.
2. Formula for Percent Error
The formula to calculate percent error is:
\[
\text{Percent Error} = \left( \frac{\text{Estimated Value} - \text{Actual Value}}{\text{Actual Value}} \right) \times 100
\]
This formula consists of three main parts:
-
Estimated Value: This is the value that Teresa guessed or estimated.
-
Actual Value: This is the real or measured value.
-
Difference: This is the absolute difference between the estimated value and the actual value.
3. Identify the Values
In this problem:
- Teresa estimated the giraffe's height to be 18 feet.
- The actual height of the giraffe is 16 feet.
4. Calculate the Difference
First, we find the difference between the estimated value and the actual value:
\[
\text{Difference} = \text{Estimated Value} - \text{Actual Value} = 18 - 16 = 2 \text{ feet}
\]
This means Teresa's estimate was 2 feet higher than the actual height.
5. Plug the Values into the Formula
Now we substitute the values into the formula:
\[
\text{Percent Error} = \left( \frac{2}{16} \right) \times 100
\]
Here, \(2\) is the difference we calculated, and \(16\) is the actual value.
6. Calculate the Fraction
Next, we compute the fraction:
\[
\frac{2}{16} = 0.125
\]
This tells us that 2 feet is 0.125 times the actual height of the giraffe.
7. Convert to Percentage
To express this as a percentage, we multiply by 100:
\[
\text{Percent Error} = 0.125 \times 100 = 12.5
\]
Conclusion
So, the percent error in Teresa's estimate of the giraffe's height is 12.5%. This means that her estimate was off by 12.5% from the actual height of the giraffe.
When rounding to the nearest tenth, we still get 12.5% as the final answer.
Thus, the final answer is \( \boxed{12.5} \) percent.