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Weighted average
Message posted by Michele Lodin on February 12, 2000 at 12:00 AM (ET)
How do I calculate a weighted average?
READERS RESPOND:
(In chronological order. Most recent at the bottom.)
Re: Weighted average
Message posted by Gene Sprechini on February 12, 2000 at 12:00 AM (ET)
To calculate an ordinary average of numbers x1, x2, ... xn, you just add them and divide by n, that is,
SUM(xi)/n
To calculate a weighted average of numbers x1, x2, ... xn, you must have respective weights w1, w2, ... wn. The weighted average is then calculated by multiplying each weight w times the corresponding x and dividing the sum of these products by the sum of the weights, that is,
SUM(wi*xi)/SUM(wi)=1.
Correction
Message posted by Gene Sprechini on February 12, 2000 at 12:00 AM (ET)
In my previous response, please ignore the =1 ant the end of the last formula. It is a rypo and does not belong there.
Re: Weighted average
Message posted by Kae Keister on February 19, 2000 at 12:00 AM (ET)
As a teacher in reference to my classroom tests is this weighting applied to each item(which I'm sure is yes) but how does it impact on the student's end score. So is n the number of items?
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