Percent Error
Definition
The percent error expresses the difference between an approximate or measured value and the exact value. To find the percent error you must first find the greatest possible error.
Approximate Error v. Exact Error
Exact error is found by subtracting the approximate value from the exact value. Negative signs should be ignored. If I made an approximation of $350 and the actually value is $400:
350 - 400 = -50
We would ignore the negative sign therefore the exact error is 50.
Percentage Error
The percentage error allows you to see the error as a percent of the exact value. To find the percentage error, we divide the exact error by the exact value:
50/400 = .125 or 12.5%
