Question

grover has scores of 72, 86, and 78 on 3 tests. what score must he make on the next test in order to have an average of 80?

Answer 1

Let x = the next score

If    (72 + 86 + 78 + x) ÷ 4 = 80

⇒   236 + x = (80 × 4)

⇒  236 + x = 320

⇒  x  = 320 - 236
         = 84

∴ he needs to get 84 on the next test to get an 80 average