To calculate the percent error in the meteorologist's forecast, we use the formula:

$\text{Percent Error} = \left( \frac{|\text{Actual Value} - \text{Forecasted Value}|}{\text{Actual Value}} \right) \times 100$

Here, the actual temperature on Monday was 80°F, and the forecasted temperature was 76°F. Substituting these values:

$\text{Percent Error} = \left( \frac{|80 - 76|}{80} \right) \times 100 = \left( \frac{4}{80} \right) \times 100 = 0.05 \times 100 = 5\%$

So, the percent error in the forecast is 5%.

Would you like further details or explanations?

Here are five related questions:

1. How do you calculate the absolute error in a forecast?
2. What are other uses of percent error in scientific calculations?
3. How does percent error differ from percent change?
4. How does rounding affect percent error in forecasts?
5. How does margin of error factor into meteorological predictions?

Tip: Percent error is always expressed as a positive value, since it represents the magnitude of the difference, regardless of direction.