A (probably easy) math question.

No, this isn’t homework and no, you aren’t helping me figure out my / my friends grades. I’ve seen this done a lot in college classes, and am just curious how an instructor makes these calculations.

Let’s say a college student is taking some random class, with the grading as follows:

Notebook/journal keeping: 10%
Research paper: 20%
Midterm: 30%
Final: 30%
Class attendance/ group discussion 10%

So, at the end of the term but BEFORE the final and notebooks are graded this student has, say, a 90% overall in the class. So, 60% of the work done so far has earned him/her a 90%.

Let’s say that the notebook is crap and gets a 0% and the final test earns, say an 85%.

What’s the formula to figure out what the final grade (%) will be? What if the notebook grade changes to a 25% or 50% or whatever%, or the final test grade changes?

90% of 60 is 54% (of the entire class).

85% of 30 is 25.5 points, added to the 54% is 79.5%.

25% of 10 is 2.5 points. 50% would be 5 points. Add that to the 79.5%.

Each component’s grade is multiplied by the points for each component. (Getting a 76% on the final would get you 76%*30 = 22.8). Then just add them up.

So apparently you’re claiming that the research paper (20%), the midterm (30%), and class attendance/group discussion (10%) are collectively at a 90 out of a 100 level. This says that 60% of the grade is at a 90 out of 100 level. You’re also saying that the notebook (10%) is at a 0 out of 100 level and the final (30%) is a a 85 out of 100 level. So then the following equation should give us the overall grade (100%):

(60% times 90) + (10% times 0) + (30% times 85) = 100% times (Overall Grade)

That reduces to this:

(.6 times 90) + (.1 times 0) + (.3 times 85) = 1 times (Overall Grade)

That reduces to this:

54 + 0 + 25.5 = Overall Grade

So the overall grade is 79.5 out of 100.

The general formula would be:

Final grade = The sum of [Score * WeightingFactor] for each performance component

This is what’s known as a weighted mean (or average).