weighted averages

[wfbberzerker]

what are weighted averages and how do they work?

 

[Robert01]

[Edited due to not relating to post. See below.]

 

[wfbberzerker]

no no no, not what i meant

i mean like:

if 8 students get 100% on a test, and 2 get 80%, how is the average affected?

 

[Radiohead]

sum( value x % weight)
= ------------------------------ I think this is how you compute it.
sum( % weight)

Pretty much weighted averages are when each value (X) you find has a different weight (w) or pull on your final value. Just think of it like your grades:

(x) (w)
Midterm Exam 30%
Final Exam 40%
Assignments 15%
Quizzes 15%

So the mark you receive for each (X) values (midterms, final, assign. & quizzes) will have a different weight (W) towards your final grade.

I hope this helped...

 

[erub]

For some reason Radiohead's method doesn't look correct to me

To do your problem

8(1.00) + 2(.80)
-----------------------
10

would give you the weighted avg.

 

[Radiohead]

I took too long to reply there
My method mentioned above would not work here being that the weight in his question would not be the %, but the numbe of students. The method I mentioned above was just an example of what weighted averages are.

But for his question, the weight(W) would be the # of students for each %, and (X) would be the % they scored, so it would look like this:


(100% * 2)+(80%*8)
--------------------------- = 8.4/10 = .84%
10


So the overall class average would be 84%

 

[wfbberzerker]

i see, so i get how to do it now, but what IS a weighted average exactly?

 

[Radiohead]

Exactly what it says it is: a mean (average) computed with the different scores assigned different weights.

 

[kranky]

A nice simple example is on this page.

 

[wfbberzerker]

hey wow kranky i was just looking at that page and got it figured out

thanks everyone

 

[Radiohead]

And I'm chop suey??? sniff sniff