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Math Help - socks

  1. #1
    Newbie
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    Question socks

    before the holidays end i thought i might brush up on some light revision and now it seems i'm stuck, i've tried karnough maps and the tree diagram but i can't seem to solve this.

    Question:
    A drawer contains 30 red socks and 20 blue socks.
    If a sock is chosen at random, its colour noted, the sock replaced and a second sock is withdrawn, what is the probability that both socks are red?
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  2. #2
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    e^(i*pi)'s Avatar
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    West Midlands, England
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    Because we have replacement we can treat the events (draws) as independent akin to tossing a coin twice.

    P(RR) = [n(red)/n(total)]^2
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  3. #3
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    ah now i see my problem, thanks mate
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