SOLUTION: How do You Solve this equation 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 m

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Question 164450: How do You Solve this equation
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 be earn on the fourth test?
a.85
b.86
c.87
d.92
e.93
Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
You are given 3 scores and asked to find a fourth that results in an average of 87.
The easiest way to go is :
Let X be the fourth test score
AveragePerTest+=+%28Total+Score%29%2F%28NumberOfTests%29
87+=+%2887+%2B+81+%2B+88+%2B+X%29%2F+4+
87+%2A+4+=+%28256+%2B+X%29+
348+=+256+%2B+X+
348+-+256+=+X+
92+=+X+
better get studying to Ace that thing