Percent Error

Percent ErrorAt the conclusion of our time together, you should be able to:

1.Define experimental error, relative error and percent error

2. Determine percent error for an experiment

How to Determine Experimental Error

Error = experimental – accepted value

Percent Error

% Error = (experimental – accepted) x 100

accepted value

Example of Percent Error

Your instructor has just massed a penny using 3 different balances. One balance measured 2.3 g, another measured 2.55 g and a third measured 2.49865 g. Determine the average mass of the penny.

2.3 g + 2.55 g + 2.49865 g =7.34865 g ?

7.3 g/3 =

2.4333333 g ?2.4 g

Example of Percent Error

Ex. Err. = 2.4 g – 2.520 g = -0.12 g

Rel. Err. = -0.12 g

2.520 g = -0.047619

= -0.048

% Err. = -0.048 x 100

= -4.8 % error

If the standard mass of a United States penny is 2.520 g, determine the experimental error, relative error and percentage error in the measurements.

Percent ErrorLet’s see if you can:

1.Define experimental error, relative error and percent error

2. Determine percent error for an experiment

Exit Quiz Percent Error

Your instructor has just measured the diameter of a dime using 3 different measuring devices. A ruler measured the diameter as 17.9 mm, a caliper measured 17.7 mm and a micrometer measured 17.788 mm. Determine the average diameter with the correct number of significant figures.

17.9 mm + 18.0 mm + 17.788 mm = 53.688 mm ?

53.7 mm/3 =

17.9 mm ?17.9 mm

Exit Quiz Percent Error

Ex. Err. = 17.9 mm – 17.80 mm = 0.10 mm

Rel. Err. = 0.1 mm

17.80 mm = 0.056179775

= 0.06

% Err. = 0.06 x 100

= 6 % error

If the standard diameter of a United States dime is 17.80 mm, determine the experimental error, relative error and percentage error in the measurements.