During a laboratory experiment, a student measures the thickness of a glass slide as 2.5\t… — JAMB UTME

During a laboratory experiment, a student measures the thickness of a glass slide as $2.5\text{ mm}$ . If the actual thickness of the slide is $2.0\text{ mm}$ , what is the percentage error in the measurement?

A
$20.0\%$
$25.0\%$ Answer
C
$0.25\%$
D
$5.0\%$

Answer

The percentage error in the measurement is

25.0\%

Percentage error is determined by dividing the absolute error (

|2.5\text{ mm} - 2.0\text{ mm}| = 0.5\text{ mm}

) by the actual value (

2.0\text{ mm}

) and multiplying by

100\%

. This gives

\frac{0.5}{2.0} \times 100\% = 25.0\%

Step-by-Step Solution

Calculate the absolute error in the measurement

\text{Absolute error} = |\text{Measured value} - \text{Actual value}| = |2.5\text{ mm} - 2.0\text{ mm}| = 0.5\text{ mm}

Absolute error measures the magnitude of discrepancy between measured and true values.

Calculate the percentage error relative to the actual value

\text{Percentage error} = \frac{\text{Absolute error}}{\text{Actual value}} \times 100\% = \frac{0.5\text{ mm}}{2.0\text{ mm}} \times 100\% = 25.0\%

Percentage error is defined as the absolute error divided by the accepted actual value, expressed as a percentage.

Key Concept

Percentage Error Calculation

Estimated Time:45s

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