SOLUTION: If a student has grade of 90,78, and 82 on the first three math test, what steps would you take to find the grade the student must get on her fourth math test to have an average of

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Question 285148: If a student has grade of 90,78, and 82 on the first three math test, what steps would you take to find the grade the student must get on her fourth math test to have an average of 90?
Found 2 solutions by stanbon, richwmiller:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
If a student has grade of 90,78, and 82 on the first three math test, what steps would you take to find the grade the student must get on her fourth math test to have an average of 90?
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Let 4th test grade be "x".
Equation:
(90+78+82+x)/4 = 90
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(250+x) = 360
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x = 110
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Cheers,
Stan H.

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
A different way to solve it is which shows why is:
To get an average of 90 we find out how much he other score was above or below 90
90 even
78 -12
82 -8
total -20
so on the next test the student must get 90+20=110
not very likely
The best the student can hope for of course is 100 which would give an average of 87.5.