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anonymous

  • 5 years ago

Ivanna has scored 85, 81, 82, and 94 on her previous four tests. What score does she need on her next test so that her average (mean) is 84 ?

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  1. anonymous
    • 5 years ago
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    Averages are found by adding up all the pieces and dividing by the number of terms added...

  2. anonymous
    • 5 years ago
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    ... so (85 + 81+ 82 + 94 + x)/5 = 84 and solve

  3. anonymous
    • 5 years ago
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    ...solve by multiplying both sides by 5 and then subtracting all the numbers on the left from each side

  4. anonymous
    • 5 years ago
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    which is....?

  5. anonymous
    • 5 years ago
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    wait why multiply

  6. anonymous
    • 5 years ago
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    because 5 is in the denominator (dividing) on the left, so you "undo" that by multiplying. ...there's another method...

  7. anonymous
    • 5 years ago
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    whats the other method

  8. anonymous
    • 5 years ago
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    ok so i came out with 1710=420????/ what did i do wrong

  9. anonymous
    • 5 years ago
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    oh wait is the answer 68?

  10. anonymous
    • 5 years ago
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    NEVER mind i got the right answer thanks!

  11. anonymous
    • 5 years ago
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    Sorry, I got pulled away, the other method is to keep track of how far above or below 84 each number is: 85 - 84 = 1 81 - 84 = -3 82 - 84 = -2 94 - 84 = 10 Then add up all of these, being careful about negatives = 1 - 3 - 2 + 10 = 6 So Ivanna has 6 extra points, which means she can get 84 - 6 = 78

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spraguer (Moderator)
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