Question

Paul has grades of 63 and 81 on his first two tests. What must he score on his third test in order to have an average of at least 70

Answer 1

(60+81+s)/3≥70  multiply both sides by 3

60+81+s≥210  combine like terms on left side

141+s≥210  subtract 141 from both sides

s≥69

So Paul will have to score 69 or more on his next test in order to have an average of at least 70.

Answer 2

To get an average of at least a 70, Paul would have to get at least a 66 on his third test.