Mathematics
Grade 9
15 min
Percent error area and volume
Percent error area and volume
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Define absolute, relative, and percent error in the context of measurement.
Determine the absolute error of a measurement based on its stated precision.
Calculate the minimum and maximum possible values for area given a linear measurement with error.
Calculate the minimum and maximum possible values for volume given a linear measurement with error.
Calculate the percent error for a calculated area or volume.
Explain how measurement error is magnified when calculating area and volume.
Ever bake a cake and have it overflow the pan? 🎂 A tiny miscalculation in the pan's volume can lead to a big mess!
This tutorial explores how a small error in a simple length measurement can grow into a much larger percent error when we calculate area or volume. Unders...
2
Key Concepts & Vocabulary
TermDefinitionExample
Measurement ErrorThe difference between a measured value and the actual (true) value. Since the true value is often unknown, we work with the possible range of error.If a ruler is slightly warped, it might measure a 10 cm line as 10.1 cm. The measurement error is 0.1 cm.
Absolute ErrorThe maximum possible difference between the measured value and the true value. It is typically half of the smallest unit of measurement.A length is measured as 15 cm to the nearest centimeter. The smallest unit is 1 cm, so the absolute error is 1 cm / 2 = 0.5 cm.
Measured ValueThe value obtained directly from a measuring instrument.You measure a table's width with a tape measure and get 85.2 cm. This is the measured value.
Maximum & Minimum Possible ValuesThe range in which the...
3
Core Formulas
Absolute Error from Precision
Absolute Error = \frac{\text{Smallest unit of measurement}}{2}
Use this to find the potential error when a measurement is given 'to the nearest' unit (e.g., nearest cm, nearest mm).
Percent Error Formula
\text{Percent Error} = \frac{\text{Maximum Error in Calculation}}{\text{Calculated Measured Value}} \times 100\%
This is the primary formula for this topic. For area/volume, the 'Maximum Error' is the difference between the maximum possible calculated value and the measured calculated value.
4 more steps in this tutorial
Sign up free to access the complete tutorial with worked examples and practice.
Sign Up Free to ContinueSample Practice Questions
Challenging
A cube has a measured side length of 5.0 cm. The percent error in its calculated volume is found to be approximately 18.9%. Working backward, what was the absolute error of the initial side length measurement?
A.±0.1 cm
B.±0.3 cm
C.±0.5 cm
D.±0.05 cm
Challenging
A cube has a side length measured to be 10 cm to the nearest centimeter. What is the percent error in its calculated total surface area? (Surface Area = 6s²)
A.10.25%
B.5.00%
C.15.76%
D.21.00%
Challenging
The volume of a cylinder is given by V = πr²h. The radius is measured as 5.0 cm and the height as 10.0 cm, both with a possible error of ±0.1 cm. What is the percent error in the calculated volume?
A.2.00%
B.4.04%
C.5.08%
D.3.00%
Want to practice and check your answers?
Sign up to access all questions with instant feedback, explanations, and progress tracking.
Start Practicing Free