How do I Calculate a Test As 20% of a Grade?

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Teachers in high school and college often calculate semester grades by assigning weights to assignments throughout the semester and computing a weighted average, or weighted mean. For example, a teacher might make the midterm test worth 20 percent of the total grade, the final exam worth 25 percent, regular homework assignments worth 40 percent and in-class participation worth 15 percent. If you knew your scores in each of these categories, you can find out your grade by calculating a weighted value for each category.

Calculating the Grade

To calculate the weighted value of any grade, you just need to multiply the percentage score you got on the assignment by the proportionate value of that assignment.

First, calculate the percentage you received on the test by dividing your mark by the total marks. For example, if you scored 18 out of 20, then 18/20 = 90 percent.

Secondly, multiply your percentage score on the test by the percentage it is worth of the final grade. For example, if you got a score of 90 percent on the test and the test is worth 20 percent of your overall grade, you would multiply 90 by 0.2 for a value of 18 points out of the possible 20 points.

If you got full credit for all your homework assignments, the weighted value for that category would be 40 points (100 x 0.4 = 40). If you managed to earn 80 percent of the possible participation points, you could add 12 points to your score (80 x 0.15 = 12), and your grade of 75 on the final exam will contribute another 18.75 points (75 x 0.25 = 18.75). Add all these points together, and you'll see that your final grade is 88.75 points out of a possible 100.


About the Author

Nick Robinson is a writer, instructor and graduate student. Before deciding to pursue an advanced degree, he worked as a teacher and administrator at three different colleges and universities, and as an education coach for Inside Track. Most of Robinson's writing centers on education and travel.