Finding Percent Error
 Units to compare:
 English Unit
yards
to
feet
to
inches
to
Metric Unit
meters
decimeters
centimeters
 In a perfect world, there are actually:
 0.91 meters in one yard
 3.048 decimeters in one foot
 2.54 centimeters in one inch
 To find percent error:
 Step 1:
 Take your metric measurement divided
by your English measurement.
 Height of book:
 11.2 inches
 28.3 centimeters

28.3 ÷ 11.2 = 2.53
 Step 2:
 Take your result minus the actual
number for the units you are using.
 Actual for inches and centimeters is 2.54.
 2.53 – 2.54 = -0.01
 Step 3:
 You might end up with a negative
number, so take the negative sign off.
 -0.01 = 0.01
 Step 4:
 Take your result divided by the actual
number for the units you are using.
 0.01 ÷ 2.54 = 0.0039
 Step 5:
 Change this number into a percent by
multiplying it by 100 (or by moving the
decimal point two places to the right –
same answer)
 0.0039 x 100 = 0.39%
 Step 6:
 Check. Is your answer less than 10%?
 For this lab, having less than 10% error
is okay.