Rueben has scored 81 , 89 , 90 , 83 , and 77 on his previous five tests. what score does he need on his next test so that his average (mean) is 82 ?

Let x = the next score

If    (81 + 89 + 90 + 83 + 77 + x)  ÷  6 = 82

  ⇒  420 + x = (82 × 6)

  ⇒  x = 492 - 420
     
       x = 72

Thus to get an 82 average he need to get 72 on his next test.

Letter c hope it

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