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The SUMPRODUCT function is one of the hardest ones to understand in Excel, but it's also pretty useful. This blog gives clear examples of how to use SUMPRODUCT for conditional sums, weighted averages and the like.
Posted by Andy Brown on 01 November 2013
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Weighted averages using the SUMPRODUCT function
The SUMPRODUCT function provides by far the best way to calculated weighted averages in Excel. Here's how!
We want to calculate the average value of sales for the following highly authentic figures:
The sales figures for 5 must-have Christmas presents.
The average price is 503.80 pounds, but this doesn't reflect the fact that we've sold only one Ducati, but 82 fur mittens:
This average price isn't realistic.
The elegant solution!
Instead, we want to calculate the weighted average price:
The average price is 503.80 pounds, but weighted by the quantities bought it's 134.55 pounds.
The statistical formula for the weighted average is:
There's really no other easy way to do this in Excel!
Hope you've enjoyed learning (or refreshing your knowledge) about SUMPRODUCT - maybe I'll be brave and write a blog about the INDIRECT function next!