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    Interesting probability question I need help with...




    Hi all, new to the forum so please excuse any newbie traits I might have..

    I have a question I need help with as I'm sure I'm missing something..

    The probability of result X happening is consistently 5%

    So if there are 1,000 events in a day you'd expect around 50 X results I think

    However, if I only randomly pick 100 from the 1,000 events in the day, then is the probability of finding result X still 5%, or 5 from 100?? or could the fact that I'm only picking 10% of the events in a day mean that the 50 expected X results from 1,000 could ALL be in the 900 I DON'T choose on the day??

    each event is a separate entity and not related

    I hope someone with more knowledge then me can help, this has been bugging me for a while now

    all the best

    TonyT1965

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    Re: Interesting probability question I need help with...

    Quote Originally Posted by TonyT1965 View Post
    the 50 expected X results from 1,000 could ALL be in the 900 I DON'T choose on the day??
    That would be unexpected.

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    Re: Interesting probability question I need help with...

    Sounds like you want to read up on the binomial distribution.
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    Re: Interesting probability question I need help with...


    And this is why not to use a Poisson?
    http://www2.cedarcrest.edu/academic/...inks/BvsP.html

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