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

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

Practice Problems 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? Remember: (EV-AV) X 100 = PE AV

Answer (EV-AV) X 100 = PE AV (22.7-21.8) X 100 = PE 21.8

More Practice 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 (EV-AV) X 100 = PE AV (.235 - .135) X 100 =PE .135