Questions about percents

Question

A friend has a 80% average before the final exam for a course. That score includes everything but final, which counts for 15% of the grade. What is the best course grade for your friend to earn? What is the minimum score would your friend need on the final to earn a 75% for the course?

Answer 1

The 80% average your friend has now equals 85% of the total grade. This is because we know the only thing left is the final which is worth 15%.

The best course grade your friend could earn will happen if they get a 100 on the final:

0.85(80%) + 0.15(100%) = 83%. The best possible grade for the course is 83%.

In order to get a 75, solve the following equation for 'f' where 'f' is the score on the final exam:

0.85(80%) + 0.15(f) = 75%

68% + 0.15f = 75%

0.15f = 7%

f = 46.67%

The minimum score needed on the final to get 75% for the course is 46.67%.