Boris has scored 80, 93, 63, 83, and 83 on his previous five tests. what score does he need on his next test so that his average (mean) is 79?

Current average = (80 + 93 + 63 + 83 + 83) / 5
= 402 / 5
= 80.4

79 x 6
= 474

what he needs to score on the next test = 474 - 402
= 72

{reassurance = (80 + 93 + 63 + 83 + 83 + 72) / 6
= 474 / 6
= 79}