How this is calculated

A simple average adds the percents and divides by how many there are. A weighted average multiplies each percent by its weight, then divides by the sum of weights.

simple: (p1 + p2 + …) / n; weighted: Σ(value × weight) / Σ(weight)

  1. 80 and 90: (80 + 90) / 2 = 85.
  2. 80 with weight 2 and 90 with weight 1: (160 + 90) / 3 = 83.333…%.
  3. 70, 80, and 90: (70 + 80 + 90) / 3 = 80.

Do not use this tool to find 15% of 80. That is percent of a number, not an average of percents.

Not the same as

An average of percentages is a mean. A percent of a number is a product.

Average-percentage questions

85%.

83.333…%. (80 × 2 + 90 × 1) / 3.

Yes. Convert each paper to a percent first, then average. Use weights if the papers have different credit.

Open marks percentage

No. 15% of 80 is 12. The average of 10% and 20% is 15%, which is still a percent, not an amount.

Open percent of a number

The weighted average cannot run, because it would divide by zero.

80%.