Question 1045249: If I have an 77, 82, 72, 63, 90, what grade do I need on the final to have an 80 average?
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! average=total/n
an 80 average for six tests (five have been taken so far)
80=total/6
multiply both sides by 6, and the total needed is 80*6=480
The current total is 77+82+72+63+90=384
you need 480
480-384=96
You need a 96
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Check
the first test is -3 from 80
the second is +2
the third is -8
the fourth is -17
the fifth is +10
The minuses add to -28, the pluses to +12. You are -16 and need +16 (above 80, which is 96) to get an average of 80
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