Which formula correctly computes Percent Error?

Which formula correctly computes Percent Error?

• A. ((experimental - accepted) / accepted) × 100
• B. ((experimental - accepted) × 100) / accepted
• C. (|experimental - accepted| / accepted) × 100
• D. (|accepted - experimental|) × 100

Answer: (C)

Percent error measures how far your experimental value is from the accepted value, expressed as a percentage of the accepted value. The key is the magnitude of the deviation, not its direction, so you use the absolute value of the difference. The correct form is the absolute difference between experimental and accepted, divided by the accepted value, times 100. This yields a nonnegative percentage that’s normalized to the true value. For example, with an experimental value of 92 and an accepted value of 100: |92 − 100| / 100 × 100 = 8%. If you omit the absolute value, you’d get a signed result (negative when the measurement is lower than the true value), which isn’t the standard way percent error is reported. A formula that multiplies the absolute difference by 100 without dividing by the accepted value wouldn’t give a proper percentage of the true value.

Percent error measures how far your experimental value is from the accepted value, expressed as a percentage of the accepted value. The key is the magnitude of the deviation, not its direction, so you use the absolute value of the difference. The correct form is the absolute difference between experimental and accepted, divided by the accepted value, times 100. This yields a nonnegative percentage that’s normalized to the true value.

For example, with an experimental value of 92 and an accepted value of 100: |92 − 100| / 100 × 100 = 8%. If you omit the absolute value, you’d get a signed result (negative when the measurement is lower than the true value), which isn’t the standard way percent error is reported. A formula that multiplies the absolute difference by 100 without dividing by the accepted value wouldn’t give a proper percentage of the true value.