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Weighted Average Calculator — Values, Weights, Contributions & Plain Average
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Calculated result
Weighted average 84.3
Weighted sum Σ(x×w): 8,430
Total weight Σw: 100 · Rows: 3
Plain unweighted average: 85 · Weighting shift: -0.7
Largest weight: Final — 50 (50% of total)
Weights total 100, so they can be read directly as percentages.
Contribution audit
| Label | Value | Weight | Weight % | Value × weight | Contribution |
|---|---|---|---|---|---|
| Homework | 92 | 20 | 20% | 1,840 | 18.4 |
| Midterm | 78 | 30 | 30% | 2,340 | 23.4 |
| Final | 85 | 50 | 50% | 4,250 | 42.5 |
Show the working
- 1. Multiply each value by its matching weight and add the products: Σ(x×w) = 8,430.
- 2. Add the weights: Σw = 100.
- 3. Weighted average = Σ(x×w) ÷ Σw = 8,430 ÷ 100 = 84.3.
Weights may be percentages, credits, quantities, frequencies or other consistent nonnegative scales. Their scale cancels during normalization, but mixing incompatible kinds of weights can make the result meaningless.
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