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Percentage Error Calculator

(True Value)


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(Observed Value)


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How to use this Percentage Error Calculator 🤔

  1. Enter ✎ value for True Value (X).
  2. Enter ✎ value for Observed Value (Y).
  3. As soon as you enter the required input value(s), the Percentage Error is calculated immediately, and displaed in the output section (present under input section).

Calculating Percentage Error

Percentage error is a measure used to express the difference between a true or theoretical value and an observed or experimental value. It is often used in scientific experiments, statistical analysis, and quality control to assess the accuracy of measurements or predictions.

The formula to calculate the percentage error is expressed as:

\( \text{Percentage Error} = \dfrac { X - Y }{ X } \times 100 \)

where:

  • X represents the true or theoretical value.
  • Y represents the observed or experimental value.

By subtracting the observed value from the true value, dividing by the true value, and then multiplying by 100, you obtain the percentage error.

Examples

The following examples demonstrate how to calculate the percentage error between a true value and an observed value using the given formula.

1. A chemist measures the boiling point of a liquid to be 102°C, but the true boiling point is known to be 100°C. What is the percentage error in the chemist's measurement?

Answer

Given:

  • X = 100°C (True boiling point)
  • Y = 102°C (Observed boiling point)

The formula to calculate the percentage error is:

\( \text{Percentage Error} = \dfrac { X - Y }{ X } \times 100 \)

Substituting the given values into the formula:

\( \text{Percentage Error} = \dfrac { 100 - 102 }{ 100 } \times 100 \)

Simplifying further:

\( \text{Percentage Error} = \dfrac { -2 }{ 100 } \times 100 = -2\% \)

Therefore, the percentage error in the chemist's measurement is -2%, indicating that the observed value is 2% higher than the true value.

2. A student calculates the density of a metal to be 7.8 g/cm³, but the true density of the metal is 8.0 g/cm³. What is the percentage error in the student's calculation?

Answer

Given:

  • X = 8.0 g/cm³ (True density)
  • Y = 7.8 g/cm³ (Observed density)

The formula to calculate the percentage error is:

\( \text{Percentage Error} = \dfrac { X - Y }{ X } \times 100 \)

Substituting the given values into the formula:

\( \text{Percentage Error} = \dfrac { 8.0 - 7.8 }{ 8.0 } \times 100 \)

Simplifying further:

\( \text{Percentage Error} = \dfrac { 0.2 }{ 8.0 } \times 100 = 2.5\% \)

Therefore, the percentage error in the student's calculation is 2.5%, indicating that the observed value is 2.5% lower than the true value.

3. In a physics experiment, the acceleration due to gravity is measured to be 9.6 m/s², while the standard value is 9.8 m/s². What is the percentage error in the measured value?

Answer

Given:

  • X = 9.8 m/s² (True value of acceleration due to gravity)
  • Y = 9.6 m/s² (Observed value)

The formula to calculate the percentage error is:

\( \text{Percentage Error} = \dfrac { X - Y }{ X } \times 100 \)

Substituting the given values into the formula:

\( \text{Percentage Error} = \dfrac { 9.8 - 9.6 }{ 9.8 } \times 100 \)

Simplifying further:

\( \text{Percentage Error} = \dfrac { 0.2 }{ 9.8 } \times 100 = 2.04\% \)

Therefore, the percentage error in the measured value of gravity is 2.04%, indicating that the observed value is 2.04% lower than the true value.

4. A laboratory scale shows a mass of 250 grams for a sample, but the true mass of the sample is 245 grams. What is the percentage error in the mass measurement?

Answer

Given:

  • X = 245 grams (True mass)
  • Y = 250 grams (Observed mass)

The formula to calculate the percentage error is:

\( \text{Percentage Error} = \dfrac { X - Y }{ X } \times 100 \)

Substituting the given values into the formula:

\( \text{Percentage Error} = \dfrac { 245 - 250 }{ 245 } \times 100 \)

Simplifying further:

\( \text{Percentage Error} = \dfrac { -5 }{ 245 } \times 100 = -2.04\% \)

Therefore, the percentage error in the mass measurement is -2.04%, indicating that the observed value is 2.04% higher than the true value.

Formula

To calculate the percentage error, you can use the following formula.

\( = \) \( \dfrac { X - Y }{ X } \times 100 \)

where

Calculation

Once you enter the input values in the calculator, the output parameters are calculated.