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anonymous

  • 5 years ago

The accompanying table shows the scores on a classroom test. What is the population standard deviation x: 100, 95, 90, 80, 75, 72, 70 f: 7, 2, 10, 4, 2, 3, 4

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  1. anonymous
    • 5 years ago
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    ooh statistics.....dont remember this but tiere's a formula for Standard Deviation...google it lol

  2. anonymous
    • 5 years ago
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    f stands for frequency, so that's the number of x' of that particular value that occurred. So x = 100 occurred 7 times in the population. x = 95 occurred twice. And so on. Find the mean of your population is the first step. That means summing over all the scores of the class and dividing by the class size.

  3. anonymous
    • 5 years ago
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    \[\sum_{n=1}^{3}i^(n-1)\]

  4. anonymous
    • 5 years ago
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    that should read i^(n-1)

  5. anonymous
    • 5 years ago
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    what's that?

  6. anonymous
    • 5 years ago
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    sum?

  7. anonymous
    • 5 years ago
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    What is that sum for formula for?

  8. anonymous
    • 5 years ago
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    the top part means you do the formula on the right 3 times using n=1 n=2 n=3 and then add up all those values

  9. anonymous
    • 5 years ago
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    but the i is raised to the n-1

  10. anonymous
    • 5 years ago
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    What's the formula represent? Is this a different problem? I thought you were asking about standard deviation.

  11. anonymous
    • 5 years ago
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    yeah its a different problem i figured out the other one ill use my calculator

  12. anonymous
    • 5 years ago
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    So what's the sum asking you to do? You want to find an explicit formula for the sum?

  13. anonymous
    • 5 years ago
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    no you need to find the sum of all those terms

  14. anonymous
    • 5 years ago
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    I have a feeling you wrote the problem wrong. As it is, it makes no sense. Unless the teacher just wants you to write: i^(0) + i^(1) + i^(2). That's the sum.

  15. anonymous
    • 5 years ago
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    yeah u do i^1+i^2+i^3 and add them up

  16. anonymous
    • 5 years ago
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    you start with 1 because thats what n=

  17. anonymous
    • 5 years ago
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    You raise it to (n-1). So when n = 1, n-1 is 0. So the first power is 0. The next power increased by 1, so it's 1.

  18. anonymous
    • 5 years ago
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    nev ermind its fine..can you look at my probability question

  19. anonymous
    • 5 years ago
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    no i gotta go

  20. anonymous
    • 5 years ago
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    if you post it on here, someone will be sure to help. there's a lot of people on right now

  21. anonymous
    • 5 years ago
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    okk

  22. anonymous
    • 5 years ago
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    good luck

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