Standard deviation and variance
Describe how spread out a list of numbers is around its mean. Both sample and population statistics are shown.
MAKE THE FORMULA CLEAR
Weighted average, GPA and target score
Average values using their weights, or calculate stock purchase cost, a school-defined GPA or a remaining exam target. Choose the mode before preparing each line.
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Weighted mean
86
Weights show relative importance, such as credits or assessment percentages. Do not mix columns from different modes.
Total weight5
Sum of value × weight430
Number of entries2 entries
Worked steps
- Multiply each value by its own weight, then add the products.
- Divide by the sum of weights; weights need not total 100, and the number of entries is not the denominator.
Supports 1–100 entries, absolute values up to 1 billion and weights from 0 to 1 million with a positive total. Weights may be credits, decimals or percentages and are normalized by their total. This is not GPA conversion, admission rules or Taiwan's weighted stock index. For an unweighted mean, use the standard deviation tool.
Method and scope
General average is sum(value times weight) divided by sum(weights). Stock mode uses total purchase cost including buy fees divided by shares; GPA uses confirmed grade points and credits; target mode divides the remaining score requirement by the unfinished percentage weight.
Stock rows are price,shares,buy-fee; GPA rows are school-grade-points,credits; target rows are earned-mark,percentage-of-entire-course. A required mark above 100 means the current target is unattainable.
General mode allows 1-100 values, absolute values up to one billion and weights from zero to one million with positive total weight. No percentage-to-GPA conversion, admissions rule or stock index is implied; do not count purchase fees twice.
References:Wolfram MathWorld：Weighted Mean
What this helps you do
Average values using their weights, or calculate stock purchase cost, a school-defined GPA or a remaining exam target. Choose the mode before preparing each line.
What to enter
Start with values and weights, one item per line, then fill the other relevant fields in the units shown. Available calculations are General weighted average, Average stock cost including purchase fees, GPA from school-defined points, Score needed on remaining assessment.
How the calculation works
General average is sum(value times weight) divided by sum(weights). Stock mode uses total purchase cost including buy fees divided by shares; GPA uses confirmed grade points and credits; target mode divides the remaining score requirement by the unfinished percentage weight.
Worked example
For marks 80 and 90 weighted 2 and 3, enter 80,2 and 90,3 to get 86. In target mode, a completed mark of 80 worth 30% needs an average of about 87.14 on the remaining 70% to reach 85 overall.
Understanding the answer
Stock rows are price,shares,buy-fee; GPA rows are school-grade-points,credits; target rows are earned-mark,percentage-of-entire-course. A required mark above 100 means the current target is unattainable.
Scope and limitations
General mode allows 1-100 values, absolute values up to one billion and weights from zero to one million with positive total weight. No percentage-to-GPA conversion, admissions rule or stock index is implied; do not count purchase fees twice.