ShmoopTube

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Here’s your shmoop du jour, brought to you by Math Tests.

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Sometimes, your teachers grade them on a Sine Curve.

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On his last four tests, Ted scored a 71, 86, 77, and 92.

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What must he score on his fifth test to have an arithmetic mean of at least 85?

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He’s looking for the arithmetic mean;

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remember, that's the sum of the data divided by the number of data entries.

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It's another name for the AVERAGE.

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To find out what Ted must score on his fifth test—we'll call it variable T—to have

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an arithmetic mean of at least 85, we can write an equation as follows.

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85 equals the sum of all the tests: 71 plus 86 plus 77 plus 92 plus T divided by 5.

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Let's solve for T now. We start by multiplying both sides by 5.

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We get 85 times 5 is 425. Adding up 71, 86, 77 and 92 equals 326 plus T.

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Subtract 326 from both sides...and we get T equals 99.

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So 99 is our answer. Yikes. Happy cramming, Ted…

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