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Math Help - Ways of calculating Mean and Variance

  1. #1
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    Ways of calculating Mean and Variance

    Hello i am looking at ways to calculate the mean and variance of X in this instance?


    A footballer out injured has made arrangement wit the club doctor whereby in a given month he visit a knee specialist (at most one) if he has severe knee pain. The chances of having the pain in a given month 0.3 and such pains fo not affect in any pain occuring.

    X = number of visits to knee speicialist in a typical year
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  2. #2
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    Quote Originally Posted by davidrocastle View Post
    Hello i am looking at ways to calculate the mean and variance of X in this instance?


    A footballer out injured has made arrangement wit the club doctor whereby in a given month he visit a knee specialist (at most one) if he has severe knee pain. The chances of having the pain in a given month 0.3 and such pains fo not affect in any pain occuring.

    X = number of visits to knee speicialist in a typical year
    X ~ Binomial(n = 12, p = 0.3)
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  3. #3
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    Thanks Mr Fantastic

    Could i check here, in one of the similar examples in a book, the mean is calculated as follows:
    Mean1(attachement) and Mean2(attachment) for X ~ Binomial(n = 12, p = 0.3).

    Which one is correct?

    Ways of calculating Mean and Variance-mean1.bmp

    Ways of calculating Mean and Variance-mean2.bmp
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  4. #4
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    Quote Originally Posted by davidrocastle View Post
    Thanks Mr Fantastic

    Could i check here, in one of the similar examples in a book, the mean is calculated as follows:
    Mean1(attachement) and Mean2(attachment) for X ~ Binomial(n = 12, p = 0.3).

    Which one is correct?

    Click image for larger version. 

Name:	mean1.bmp 
Views:	7 
Size:	7.0 KB 
ID:	13414

    Click image for larger version. 

Name:	mean2.bmp 
Views:	5 
Size:	14.3 KB 
ID:	13415
    For Binomial(n, p) the mean is np and the variance is np(1-p).
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