In order for him to have a 77% on his first 5 tests, that means the total amount of points earned on those 5 tests was 385 points out of 500 points.
(77*5 out of 5*100 points)
So if we want to add a test and have a 80% average this is what we have to do:
(385+x)/6 = 80 (multiply by 6 on both sides)
385 + x = 480 (minus 385 on both sides)
x = 95
(77*5 out of 5*100 points)
So if we want to add a test and have a 80% average this is what we have to do:
(385+x)/6 = 80 (multiply by 6 on both sides)
385 + x = 480 (minus 385 on both sides)
x = 95
