If I have 96% overall grade in a class, and I get a 78% on an quiz that is worth 20% of my grade

Answer 1

There is no question here! Are you asking:

In my class, I had 96% going into the final quiz (worth 20%), so what will my final percentage be?

In that case, you've got 80% of the course with a score of 96% plus 20% at 78%, and your final score would be:

(0.96 * 0.80 + 0.78 * 0.20) / 1 = 0.924 = 92.4%

But it could be quite different, if you're only part way through the semester. Usually, the final 20% of a class wouldn't be called a "quiz" but rather a final exam. This sounds a bit like "My grade so far in the class has be 96, but I just took a quiz worth 20% and got a 78% on it... so now how am I doing?"

If that's the case, and the class is continuing with more grades coming in, we can't determine your score! We need to know what percentage of the class grade does the 96% represent. If it only represents 20%, well that's easy, you can just average the 96 and the 78 and see that your grade so far is 87 (halfway between the two). Whatever the percentage is that applies to the 96%, just substitute that into the formula above for the "0.80", and also reduce the divide by 1 part at the end to divide by the fraction of the class that has been completed. So for this 20% example, you'd divide by 0.20+0.20 = 0.40 (20% for the 96, another 20% for the 78).

Good luck, Paul