Question

A student has earned the following scores on four 100-point tests this marking period: 63, 72, 88, and 91. What score must the student earn on the fifth and final 100-point test of the marking period to earn an averagetest grade of 80 for the five tests?

Answer 1

In order to have average 80 score from 5 tests, student needs to have 400 points (80%*500=0.8*500=400)
So far he has 63+72+88+91= 314
400-314=86

He needs to get 86 points from the last test.
Since he is obviously getting better at tests, i think he'll manage :)