Question

A student has gotten the following grades on his tests. What is the minimum grade he must get on the last test in order to have an average of 787

83, 81, 70, 74
The minimum grade he must get on the last test in order to have an average of 78 is

Answer 1

82.

Explanation:

The sum of the 5 tests must be 5*78 = 390 for the average to be 78.

So in the last test is grade must be 390 - (83+81+70+74)

= 390 - 308 = 82.

Answer 2

82

Explanation:

The sum of his previous grades were 308. In order to get an average grade of 78, he needs to have a score of 78*5 or 390. His necessary grade minus his current grade is 390 - 308, which is 82. The minimum score the student needs to get on his test in order to have an average of 78 is 82