Question

As part of a probability experiment for math class, Reid flipped a coin a hundred times. He predicted it would land on heads 50 times, but it actually landed on heads 40 times. What is the percent error for Reid's prediction?
If necessary, round your answer to the nearest tenth of a percent.
%__

Answer 1

To calculate the percent error for Reid's prediction, we can use the formula for percent error:

\[
\text{Percent Error} = \left( \frac{\text{Actual Value} - \text{Predicted Value}}{\text{Predicted Value}} \right) \times 100
\]

In this case, the predicted value is 50 heads and the actual value is 40 heads.

1. Calculate the error:
\[
\text{Error} = \text{Actual Value} - \text{Predicted Value} = 40 - 50 = -10
\]

2. Substitute the values into the percent error formula:
\[
\text{Percent Error} = \left( \frac{-10}{50} \right) \times 100
\]

3. Simplify the calculation:
\[
\text{Percent Error} = -0.2 \times 100 = -20
\]

Since percent error is usually expressed as a positive value, we take the absolute value:

\[
\text{Percent Error} = 20\%
\]

Therefore, the percent error for Reid's prediction is:

\[
\boxed{20\%}
\]