1. How Wrong is Wrong??

2. Percent Error/Percent Deviation
My Handy Dandy Reference Table pg 1
% Deviation = ( Difference from accepted Value/Accepted Value) x 100

3. Sample Problem
1. Working in the laboratory, a student finds the density of a piece of pure aluminum to be 2.85g/cm3. The accepted value for the density of aluminum is g/cm3. What is the student's percent error?
(0.151/2.699) x 100=
5.6 %

4. Sample Problem
A 75 ml solid is estimated by a student to be 81 ml. Calculate the percent error.
(6/75) x 100 =
8.0 %

5. Error Every measurement made has some error.
As technology has advanced we have been able to improve our measurements with tools capable of measuring more precisely.

6. Keep it under 10 %
Lab measurements should be under a 10 % error to be accurate.