Weighted average

Averaging Evenly Weighted Scores
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For a concrete example, imagine you have four assignments for a course and a final exam, where each assignment is weighted at 15 percent, and the exam is 40 percent, with the maximum possible score on each being 100. Your scores on the assignments are 70, 83, 77 and 90, and for the final exam you got 65: What is your final score?

For the assignments, you multiply the scores by the decimal form of 15 percent, i.e. 0.15, giving 10.5, 12.45, 11.55 and 13.5. For the exam, you use 0.4 as the decimal form of 40 percent, and then multiply this by 65 to get 26. Your total score is then all of these added together: 10.5 + 12.45 + 11.55 + 13.5 + 26 = 74.

If your scores for a class are all weighted the same, the process is much simpler: You just take the average of all of the results to find the final score. In other words, add up all the individual scores and then divide the result by the total number of scores. For the scores in the previous example, 70, 83, 77, 90 and 65, this gives:

          70+83+77+90+65
Result = -----------------
                5