Question

Andy estimated that he would need 78 feet of lumber for a tree house project. He later found that the actual amount of lumber needed was 67 feet. What was the percent error of Andy's estimation?
A.
16.42%
B.
11%
C.
85.90%
D.
14.10%

Answer 1

To calculate the percent error of Andy's estimation, you can use the formula:

\[
\text{Percent Error} = \frac{\text{Estimated Value} - \text{Actual Value}}{\text{Actual Value}} \times 100
\]

In this case:

- Estimated Value = 78 feet
- Actual Value = 67 feet

Now, plug in the values:

\[
\text{Percent Error} = \frac{78 - 67}{67} \times 100
\]

Calculate the difference:

\[
78 - 67 = 11
\]

Now, divide by the actual value:

\[
\frac{11}{67} \approx 0.1642
\]

Finally, multiply by 100 to convert it to a percentage:

\[
0.1642 \times 100 \approx 16.42\%
\]

Thus, the percent error of Andy's estimation is approximately **16.42%**.

The correct answer is **A. 16.42%**.