Statistics
Solving for one missing value
Subtract everything already locked in from the target, then divide by whatever weight remains. Use it to answer what score or return is still needed.
The Formula
Required v = (Target - Sum of known v x w) / w for the missing item
Subtract everything already locked in from the target, then divide by whatever weight remains. Use it to answer what score or return is still needed.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| T | Target weighted average | number | The overall result you want to finish with. |
| wk | Weight still open | weight | Expressed on the same scale as the other weights — as a share if those are shares. |
What Each Symbol Means
Tnumber
Target weighted average
The overall result you want to finish with.
wkweight
Weight still open
Expressed on the same scale as the other weights — as a share if those are shares.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate a weighted average page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate A Weighted Average, filed under Math. Every number the guide produces comes from substituting into this one line.