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Weighted Mean

Author: Jonathan Osters

Source: Female Symbol; Public Domain: http://www.clker.com/clipart-6436.html

Video Transcript
Terms to Know
Mean

The "average" value of a data set. It is obtained by dividing the sum of the values by the number of values in the set.

Summation Notation

A notation that uses the Greek letter sigma to state that values should be added together.

Weighted Mean/Average

A way of calculating a mean when not all the values count for the same amount. Each value should be multiplied by its weight and added together, then divide the sum by the sum of the weights.

Formulas to Know
Mean

m e a n space equals space fraction numerator x subscript 1 plus x subscript 2 plus x subscript 3 plus times times times plus x subscript n over denominator n end fraction space equals space 1 over n sum from i equals 1 to n of x subscript i

Weighted Mean

W e i g h t e d space M e a n equals fraction numerator S u m space o f space left parenthesis W e i g h t times V a l u e right parenthesis over denominator S u m space o f space W e i g h t s end fraction