The weighted average is the mean of a set of numbers in which some numbers are worth more, or carry more weight, than others. Knowing how to calculate weighted average is beneficial when calculating grades, since different assignments, exams and quizzes often carry different weights.
Calculating Weighted Average

To calculate weighted average, multiply each number in the set by their weight and then add up the products. For example, if your teacher tells you that the assignments are worth 30 percent, the tests are worth 25 percent and the final exam is worth 45 percent, these are the weights – this is how much each of these categories contribute to your overall grade.
If your teacher has given you a grade of 70 percent for your assignments, 85 percent for your tests and 80 percent on your final exam, the equation would be:
0.30 x 70 + 0.25 x 85 + 0.45 x 80 =
21 + 21.25 + 36 =
78.25The weighted average is 78.25, which is your final grade.
References
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