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Math Help - Statistics

  1. #1
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    Statistics

    Any of you guys who feeling comfortable with anything of these?
    Im really lost

    You observe the following sample (rounded) drawn from a normal random variable
    X~N(,):

    22, 19, 14, 15, 20, 20, 21, 14, 19, 18, 15, 14, 15.


    a) Use the sample to estimate
    and .
    b) Estimate the variance of the sample average ӿ
    c) Find a 99% confidence interval for
    d) Test the null hypothesis H0: 15 against H0: ≠15 with α= 5%
    e) Test the null hypothesis H0: =0 against H0: ≠ with α= 5% for an arbitrary 0.
    f) Find the confidence interval for .

    g) How are the results in e) and f) related? Why?

    Im glad for all kind of answers!
    Last edited by mr fantastic; March 20th 2010 at 04:11 AM. Reason: Corrected post
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  2. #2
    MHF Contributor matheagle's Avatar
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    The estimate of \mu is the sample average \bar X

    while the unbiased estimate of \sigma^2 is the sample variance {\sum_{i=1}^n(X_i-\bar X)^2\over n-1}
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  3. #3
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    But I doesnt have n? X would be 4?

    And 0,05, whats that?
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  4. #4
    MHF Contributor matheagle's Avatar
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    Quote Originally Posted by Lippi86 View Post
    But I doesnt have n? X would be 4?

    And 0,05, whats that?

    you do need to open up your book
    n is the number of observation in your data set
    alpha =.05 is the probability of a type one error

    You really do need to crack open your book.
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  5. #5
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    the variance of the sample average ӿ , I cant find that in my book? is it the same as just a plan .

    because in the qusetion they asking about ... and I cant find how Im doing this? maybe it because the book is written in anoter way of doing it?
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