How to Calculate Difference
Difference quantifies how properties of two or more objects deviate from each other. It also indicates changes in characteristics (such as speed or position) of the same object. Furthermore, differences address the precision of a measurement--the deviation between exact and experimental values. Mathematically, difference is obtained using the subtraction operation.
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Instructions
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1
Calculate the difference in heights of two towers if the first one is 56 feet and the second one is 76 feet tall.
Difference=dimension (second object)-dimension (first object)
Difference=76 feet-51 feet=25 feet. -
2
Calculate difference in the car speed if the vehicle accelerates from 35 mph to 60 mph.
Difference= parameter (final state)-parameter (initial state).
Difference=60 mph-35 mph=25 mph. -
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3
Calculate an absolute error if a box was found to weigh 10 pounds while its true weight was actually 10.5 pounds. The absolute error is the difference between the true and measured values.
Absolute error=(true value)-(measured value).
In the example, the absolute error is equal to (10.5-10) .5 pounds. -
4
Calculate the relative error (difference) and percent error.
The relative error is a ratio between the difference modulus (denoted as "| |") and the true value. Relative error = |difference|/true value. Percent error is the relative error in percents.
Using the example from Step 3 obtain
Relative error=|0.5|/10.5=0.0476 and Percent error=0.0476 x 100 percent=4.76 percent. -
5
Calculate percent difference between two values using the formula.
Percent difference=100 percent x |Value1-Value2|/(Value1+Value2)/2. Note that the term "(Value1+Value2)/2" is an average of the two values.
As an example, calculate percent difference for two wooden sticks that are 1.2 and 1.5 feet in length. First, obtain the average length of the sticks: (1.2+1.5)/2=1.35 feet. Then, Percent difference =100 percent x |1.5-1.2|/1.35=22.22 percent.
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