To get a B in math, Alexandria Pappas must average 80 on five tests scores on the first four tests were 84. 77, 84, and 75. What is the lowest score that she can get on the last test and still get a B?

Oct 19, 2016

The final grade must be 83

Explanation:

To think through this logically, she wants to get a average of 80 over 5 tests. $5 \cdot 80$ = 400. We want the total of all the test grades to equal 400.
Sum up what you know to get a base.

$84 + 77 + 84 + 75$ = 317

now we want to know what will add to 317 to get 400.

$400 - 317$ = 83

So her final grade must be at least an 83 to get an average of 80 or higher.