Mac measured the density of silver three times and obtained the following results:

Question

Trial 1: 10.6 g/cm3

Trial 2: 10.8 g/cm3;

Trial 3: 9.6 g/cm3

Silver has a density of 10.5 g/cm3

A. Calculate Mac's percent error for each trial.

B. Which trial had the greatest percent error.

Answer 1

% error is the difference between the measured value and the actual value ÷ the actual value (x100%)

Trial 1: 10.6 g/cm3 ... % error = 0.1/10.5 (x100%) = 0.95%

Trial 2: 10.8 g/cm3 ... % error = 0.30/10.5 (x100%) = 2.86%

Trial 3: 9.6 g/cm3 ... % error = 0.90/10.5 (x100%) = 8.57%

B. Which trial had the greatest percent error.

Trial 3 has the greatest % error

Answer 2

Percent error is |100 * (experimental value - actual value)/ actual value|

In this case trial one has a percent error of .95%

The question should be looking for greatest magnitude of percent error. If negative percent error is considered less, then that is just bad.