Math CentralQuandaries & Queries


Question from jo:

I have a comparative report and I was confused about how to get the percentage of the current 1st quarter vs. last year 1st quarter, vs. last year of the same month. I hope you could help me, thank you.
Example: Food sales: 3Day Sale Event

TY: 1,352,293.58 May (Back to School)
LY: 1,205,614.31 April (Summer Sale)
LY: 1,065,693.40 May 2009

Hi Jo,

Change is measured as the new value minus the old value. If you want this as a proportion of the old value divide the change by the old value. To express this as a percentage you need to multiply by 100. For example from math 2009 to May 2010 the change was

1,352,293.58 - 1,065,693.40.

As a proportion of the old value this is

(1,352,293.58 - 1,065,693.40)/1,065,693.40.

Multiply this value by 100 to achieve the percentage change from May 2009 to May 2010.


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