SOLUTION: Josh has scored 65, 71, and 91 on his last three tests. what score must he get on his next exam to have an average (mean) of 80?

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Question 538086: Josh has scored 65, 71, and 91 on his last three tests. what score must he get on his next exam to have an average (mean) of 80?
Found 2 solutions by oberobic, Gurukool:
Answer by oberobic(2304) About Me  (Show Source):
You can put this solution on YOUR website!
(65+71+91+x)/4 = 80
.
(65+71+91+x) = 4*80 = 320
.
227 +x = 320
.
x = 93

Answer by Gurukool(2) About Me  (Show Source):
You can put this solution on YOUR website!
Assume he has to score X in the next exam.
Then (65 + 71 + 91 + X)/4 = 80
=> X = 80*4 - (65 + 71 + 91)
=> X = 93
So Josh has to score 93 in the next exam to have an average of 80.