SOLUTION: Leon must have made a mean score of 90 on his math quizzes to earn an A. So far, he has received grades of 88,85,91,92,94,81,86,98. What grade must he earn on his final quiz?

Question 671355: Leon must have made a mean score of 90 on his math quizzes to earn an A. So far, he has received grades of 88,85,91,92,94,81,86,98. What grade must he earn on his final quiz?

Found 3 solutions by ewatrrr, stanbon, solver91311:
Answer by ewatrrr(24785)   (Show Source): You can put this solution on YOUR website!

Hi,
(88+85+91+92+94+81+86+98 + x)/9 ≥ 90
x ≥ 90�9 - (88+85+91+92+94+81+86+98)
Answer by stanbon(75887)   (Show Source): You can put this solution on YOUR website!
Leon must have made a mean score of 90 on his math quizzes to earn an A. So far, he has received grades of 88,85,91,92,94,81,86,98. What grade must he earn on his final quiz?]
----
His final quiz will be his 9th quiz.
To average 90 he needs 9*90 = 810 points
--------
He needs 810-(88+85+91+92+94+81+86+98) = 95 on his 9th quiz
==================
Cheers,
Stan H.
Answer by solver91311(24713)   (Show Source): You can put this solution on YOUR website!

In order to have a mean score of greater than or equal to X on Y equal weight tests, then you must have a total of greater than or equal to XY. You have a list of eight exams. Presumably the "final quiz" is the only other one that has to be taken, so there are a total of 9 quizzes. Add up the scores of the quizzes already taken and subtract from 9 times 90. The result will be the score required for the desired average.

John

My calculator said it, I believe it, that settles it

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