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chocolatechip_543

The following table shows the probability distribution for a discrete random variable. X 13 16 18 21 23 25 26 31 P(X) 0.07 0.21 0.17 0.25 0.05 0.04 0.13 0.08 The mean of the discrete random variable X is 20.59. What is the variance of X? Round your answer to the nearest hundredth.

  • one year ago
  • one year ago

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  1. telliott99
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    http://math.elon.edu/statistics112/prob_dist.html

    • one year ago
  2. hal_stirrup
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    \[s2 = Σ ( x _{I} - x )2 / ( n - 1 )\]

    • one year ago
  3. hal_stirrup
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    are you there??

    • one year ago
  4. chocolatechip_543
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    yes

    • one year ago
  5. chocolatechip_543
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    can you explain the equation a bit?

    • one year ago
  6. hal_stirrup
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    sure lets star with \[\sum_{i=1}^{n}\]

    • one year ago
  7. hal_stirrup
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    do you understand what this means?

    • one year ago
  8. chocolatechip_543
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    yes

    • one year ago
  9. hal_stirrup
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    good then\[x_{i} -x\] xi is each value of your x value . -x really i cant use xbar because the keyboard is limited .. x bar is the average= \[xbar=\sum_{i=1} x _{i}/n\]

    • one year ago
  10. hal_stirrup
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    we are assuming that you have sample and not population as well !!!!

    • one year ago
  11. chocolatechip_543
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    alright..I'm a little lost now

    • one year ago
  12. hal_stirrup
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    tell me where.

    • one year ago
  13. chocolatechip_543
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    at the last part you posted

    • one year ago
  14. hal_stirrup
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    "we are assuming that you have sample and not population as well" that

    • one year ago
  15. chocolatechip_543
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    yes and before that

    • one year ago
  16. hal_stirrup
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    look. inorder to help you you need to be clear as to where are you not understanding . so i can help you better. thanks

    • one year ago
  17. chocolatechip_543
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    I'm sorry, I just don't understand it.

    • one year ago
  18. hal_stirrup
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    no need to be sorry . :)

    • one year ago
  19. hal_stirrup
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    have you done statistics before ?

    • one year ago
  20. chocolatechip_543
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    no, but this is in my algebra 2 work

    • one year ago
  21. hal_stirrup
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    thats cool/

    • one year ago
  22. hal_stirrup
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    do you now how to get the mean?

    • one year ago
  23. chocolatechip_543
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    yes

    • one year ago
  24. hal_stirrup
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    ok so were half way.

    • one year ago
  25. hal_stirrup
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    lets talk concept first. is that ok?

    • one year ago
  26. chocolatechip_543
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    sure

    • one year ago
  27. hal_stirrup
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    variance is the distance from the mean measured in squares. |dw:1343956195413:dw|

    • one year ago
  28. hal_stirrup
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    in you r case you have many data points. so really your job is fine all the distance from the mean and then sum them up and divide by the number of data point and minus 1.

    • one year ago
  29. hal_stirrup
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    s2=Σ(xI−x)2/(n−1) thats what this formula say.

    • one year ago
  30. chocolatechip_543
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    oh alright

    • one year ago
  31. hal_stirrup
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    share what your thinking if you like?

    • one year ago
  32. hal_stirrup
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    if you like to , be my fan and send my question and thoughts if you want and dont forget to click on best response . thanks @chocolatechip_543

    • one year ago
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