How to Calculate Percent Error with a Real-World Example

Math with Mr. J

This instructional math video guides students through the process of calculating percent error, a critical concept for understanding accuracy in measurements and estimations. The video begins by defining percent error and presenting the standard formula involving absolute value. It then walks through a practical, real-world word problem involving an event planner who estimated 325 guests but had 364 actual attendees, demonstrating how to apply the formula to find the percentage of error in the estimation. The video covers several key mathematical themes, including the difference between estimated and actual values, the function of absolute value in determining error magnitude, and the procedural steps of converting decimals to percentages. It also explicitly demonstrates how to round the final result to the nearest whole percent, reinforcing rules of rounding in a practical context. The step-by-step breakdown ensures that viewers understand not just the calculation, but the logic behind comparing an estimate against reality. For educators, this resource serves as an excellent direct instruction tool or review aid for middle school math curriculums. It simplifies a multi-step process—subtraction, division, and multiplication—into manageable chunks. The use of a relatable scenario helps ground abstract statistics concepts in reality, making it useful for lessons on data analysis, scientific measurement, or financial literacy where prediction versus reality is a key metric.