Question

A student has scores of 72%, and 78% on three mathematics examinations. What interval of scores does his last score need to fall in to earn a grade of B (80% or better)?

Answer 1

The student wants a grade of x on his 3rd exam, so that the average of the 3 exam grades is 80:

72 + 78 + x

---------------- = 80

3

Solving for x: 72 + 78 + x = 240, or x = 90

If the student earns a grade of 90 or better on the 3rd exam, he will earn a course grade of 80 or better.