SOLUTION: Please can you help me: problem: A student has earned scores of 87,81, and 88 on the first 3 of 4 tests. If the student wants an average (arithmetic mean) of exactly 87, what score

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Question 149782: Please can you help me: problem: A student has earned scores of 87,81, and 88 on the first 3 of 4 tests. If the student wants an average (arithmetic mean) of exactly 87, what score must she earn on the fourth test?
I need a solution of how to set the equation up and steps on how to solve the problem. Can anyone help me. Thanks
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A student has earned scores of 87,81, and 88 on the first 3 of 4 tests. If the student wants an average (arithmetic mean) of exactly 87, what score must she earn on the fourth test?
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Let the 4th test score = x
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write an average equation which states the problem
%28%2887+%2B+81+%2B+88+%2B+x%29%29%2F4 = 87
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Add up the given values:
%28%28x%2B256%29%29%2F4 = 87
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We can get rid of the denominator by multiplying both sides by 4,
x + 256 = 4*87
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x + 256 = 348
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Subtract 256 from both sides
x = 348 - 256
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x = 92 is the score required in the 4th test.
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Check our solution on a calc enter (87 + 81 + 88 + 92)/4 = 87
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