SOLUTION: Jack had an average score of 85 on his first eight quizzes, and an average score of 81 on his first nine quizzes. What score did he receive on his ninth quiz?

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Question 318497: Jack had an average score of 85 on his first eight quizzes, and an average score of 81 on his first nine quizzes. What score did he receive on his ninth quiz?
Answer by stanbon(75887) About Me  (Show Source):
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Jack had an average score of 85 on his first eight quizzes, and an average score of 81 on his first nine quizzes. What score did he receive on his ninth quiz?
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Points acquired on the 1st 8 quizzes = 8*85 = 680
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Let "x" be the score on the ninth quizz.
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Equation:
Solve for "x":
(680+x)/9 = 81
680+x = 729
x = 49
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Cheers,
Stan H.