# Math Help - Weighted Averages

1. ## Weighted Averages

What is the weighted average?

if a=50%,b=25%,c=20%,d=5%.

Value of a=136.5/255,
b = 75/75
c =19/20
d = 30/30.
I keep getting different answers. Can someone explain the right way to do this?

2. ## Re: Weighted Averages

Originally Posted by kads
What is the weighted average?

if a=50%,b=25%,c=20%,d=5%.

Value of a=136.5/255,
b = 75/75
c =19/20
d = 30/30.
I keep getting different answers. Can someone explain the right way to do this?
What value are you getting?

3. ## Re: Weighted Averages

What do "136.5/255", "75/75", "19/20", and "30/30" mean? If they are not simply fractions, which does not seem likely, what I don't know what you mean. Further, you are confusing things by using the same letters, "a", "b", "c", and "d" for both them an their respective weights.

If you had four NUMBERS, A, B, C, and D, with "weights" 50%, 25%, 20%, 5%, respectively, then the "weighted average" would be .5A+ .25B+ .2C+ .05D.

4. ## Re: Weighted Averages

Originally Posted by kads
if a=50%,b=25%,c=20%,d=5%.
Value of a=136.5/255,
b = 75/75
c =19/20
d = 30/30.
[.5(136.5/255) + .25(1) + .2(19/20) + .05(1)] / [136.5/255 + 1 + 19/20 + 1] = .2496....