Question

when kenny bought his new guinea pig, the pet store told him it would weigh about 2 pounds when fully grown. now fully grown, the guinea pig weighs 1.8 pounds. what is the percent error for the pet store’s prediction?
if necessary, round your answer to the nearest tenth of a percent.
%

Explanation:

Step1: Find the absolute error

The predicted weight is 2 pounds, and the actual weight is 1.8 pounds. The absolute error is the absolute difference between the predicted value and the actual value. So, we calculate $|2 - 1.8| = 0.2$ pounds.

Step2: Calculate the percent error

The formula for percent error is $\text{Percent Error} = \frac{\text{Absolute Error}}{\text{Predicted Value}} \times 100\%$. Substituting the values we have, the predicted value is 2 pounds and the absolute error is 0.2 pounds. So, $\text{Percent Error} = \frac{0.2}{2} \times 100\%$.
First, calculate $\frac{0.2}{2} = 0.1$. Then multiply by 100% to get $0.1 \times 100\% = 10.0\%$? Wait, no, wait. Wait, let's check again. Wait, the predicted value is 2, actual is 1.8. So the error is $2 - 1.8 = 0.2$. Then percent error is (error / predicted) 100. So (0.2 / 2) 100 = (0.1) * 100 = 10%? Wait, but let's do it step by step.
Wait, $\frac{0.2}{2} = 0.1$, then $0.1 \times 100 = 10.0\%$? Wait, but let me confirm. The formula for percent error is $\frac{|\text{Measured Value} - \text{Accepted Value}|}{\text{Accepted Value}} \times 100\%$. Here, the predicted value is the accepted value (2 pounds), and the actual (measured) value is 1.8 pounds. So the difference is $|1.8 - 2| = 0.2$. Then percent error is $\frac{0.2}{2} \times 100\% = 10.0\%$. Wait, but maybe I made a mistake? Wait, no, 0.2 divided by 2 is 0.1, times 100 is 10. So the percent error is 10.0%? Wait, but let me check again. Wait, 2 - 1.8 is 0.2. 0.2 over 2 is 0.1, times 100 is 10. So yes, that's correct.

Answer:

10.0%