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# Relative difference or percentage difference — comparing values using a percentage

This is an introduction to the concept of relative difference, or comparing two values using a percentage.

All we need to do is write the fraction DIFFERENCE/REFERENCE and then convert that into a percentage. The "difference" is the difference between the two values we are comparing. The reference value could be one of the two values, if it is clear that we are comparing one item to the other. For example, if the question is how many percent taller is the oak tree than a birch tree, then the comparison is TO the birch tree so its height is the reference value. If it's not clear which of the two is the "reference item", then you can use the average of the two values as the reference value. However, this last situation is not deal with in the video.

Percentage of change — video lesson

Math Mammoth Grade 7 curriculum (pre-algebra)

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