Calculating Percent Error What is it Percent Error

Calculating Percent Error

What is it? ? Percent Error is used to determine the inaccuracy, in percentage, of a measured or estimated value, compared to an accepted value.

The Components of the Formula l l Estimated Value (Measured Value)- The value that has been derived from an experiment, or an estimated value. Actual Value (What you should have gotten!) - This value is the exact value excepted throughout the scientific community, or the value which is determined exact, at a later point in time.

You will be setting up a fraction! So watch your parentheses if you are using a calculator!

The formula The Formula for Percent Error is a follows: l (EV – AV) X 100 = Percent Error AV Remember: EV= Estimated Value (measured value!) AV= Actual Value PS. We multiply by 100 to make the decimal a percent. l

Practice Problems l Johnny calculates from an experiment that he has 22. 7 grams of carbon. However, he should have gotten 21. 8 grams of carbon, which was the accepted value for this experiment. What was his percent error? l Remember: (EV-AV) X 100 = PE AV

Answer l (EV-AV) X 100 = PE AV (22. 7 -21. 8) X 100 = PE 21. 8. 900 X 100 = PE 21. 8. 0413 X 100 = PE 4. 13 % = PE

More Practice l The actual value for the absorption of carbon is. 135. Steven calculated that absorption was. 235. What is the percent error in Steven’s experiment?

Answer l (EV-AV) X 100 = PE AV (. 235 -. 135) X 100 =PE. 135. 100 X 100 = PE. 135. 741 X 100 = PE 74. 1 % = PE