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Marginal distribution of a discrete random variable-- statistics Watch

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    Can someone please help me figure out how this joint prob. distribution is drawn together? I know how the 0 values and the one that's given is obtained, pretty much clueless about the rest, I also know that there are 28 ways of choosing 2 refills from 8.
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    (Original post by rextra)
    ...
    Consider the cell relating to X=0,Y=0.
    If they're not blue and not red, then both choices must be green.
    So, we want P(1st choice is green) X P(2nd choice is green) = 3/8 x 2/7 = ...

    Or X=1,Y=0.
    So, one blue refill, and no red. Well, again if it's not red and it's not blue, it must be green.

    So, we want P(1st choice blue) X P(2nd choice is green) + P(1st choice is green) X P(2nd choice is blue) = 3/8 X 3/7 + 3/8 X 3/7 = ....


    I think you should be able to fill in the remainder yourself now - have a go.
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    (Original post by ghostwalker)
    Consider the cell relating to X=0,Y=0.
    If they're not blue and not red, then both choices must be green.
    So, we want P(1st choice is green) X P(2nd choice is green) = 3/8 x 2/7 = ...

    Or X=1,Y=0.
    So, one blue refill, and no red. Well, again if it's not red and it's not blue, it must be green.

    So, we want P(1st choice blue) X P(2nd choice is green) + P(1st choice is green) X P(2nd choice is blue) = 3/8 X 3/7 + 3/8 X 3/7 = ....


    I think you should be able to fill in the remainder yourself now - have a go.
    wow, thanks! posted a new q just now, if you can help me figure this one out that'd be mint x http://www.thestudentroom.co.uk/show...2#post42085002
 
 
 
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