SOLUTION: You have four scores of 82, 78, 90, and 70. What do you need to get on the fifth test in order to obtain an average score of 81 for the five tests?

SOLUTION: You have four scores of 82, 78, 90, and 70. What do you need to get on the fifth test in order to obtain an average score of 81 for the five tests?

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Question 896493: You have four scores of 82, 78, 90, and 70. What do you need to get on the fifth test in order to obtain an average score of 81 for the five tests?
Answer by richwmiller(17219) (Show Source): You can put this solution on YOUR website!
Two ways
82-81=1
78-81=-3
90-81=9
70-81=-11
1-3+9-11=-4
81+4=85
(82+ 78+ 90+ 70+x)/5=81
(320+x)/5=81
(320+x)405
x=85

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