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Math Help - Statistics Probability - DUE MONDAY

  1. #1
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    Statistics Probability - DUE MONDAY

    Relative Frequency of 0 centipede in a square = .45
    Relative Frequency of 1 centipede in a square = .36
    Relative Frequency of 2 centipede in a square = .14
    Relative Frequency of 3 centipede in a square = .04
    Relative Frequency of 4 centipede in a square = .01


    1) Now suppose that 5 squares are chosen at random. Find the probability that 3 of the squares contain centipedes and 2 contain no centipedes. (hint: think binomial)

    = 5!/(3! * 2!) * (.55^3) * (.45^2) = .34


    2) If again, 5 squares are chosen at random, what is the probability that 3 or more squares contain centipedes?

    = 5!/(3! * 2!) * (.55^3) * (.45^2) = .34

    = 5!/(4! * 1!) * (.55^4) * (.45^1) = .21

    = 5!/(5! * 0!) * (.55^5) * (.45^0) = .05


    = .34 + .21 + .05 = .60







    Is this correct? Please check my work. Thanks.
    Last edited by funnyname7; March 19th 2010 at 07:25 PM.
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  2. #2
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    Hello funnyname7
    Quote Originally Posted by funnyname7 View Post
    Relative Frequency of 0 centipede in a square = .45
    Relative Frequency of 1 centipede in a square = .36
    Relative Frequency of 2 centipede in a square = .14
    Relative Frequency of 3 centipede in a square = .04
    Relative Frequency of 4 centipede in a square = .01


    1) Now suppose that 5 squares are chosen at random. Find the probability that 3 of the squares contain centipedes and 2 contain no centipedes. (hint: think binomial)

    = 5!/(3! * 2!) * (.55^3) * (.45^2) = .34


    2) If again, 5 squares are chosen at random, what is the probability that 3 or more squares contain centipedes?

    = 5!/(3! * 2!) * (.55^3) * (.45^2) = .34

    = 5!/(4! * 1!) * (.55^4) * (.45^1) = .21

    = 5!/(5! * 0!) * (.55^5) * (.45^0) = .05


    = .34 + .21 + .05 = .60







    Is this correct? Please check my work. Thanks.
    Yes, your work is good. Well done.

    Just one thing, though: don't round off to 2 d.p. quite so soon. To 3 d.p. the answer is:
    0.337 + 0.206 + 0.050 = 0.593
    and you'll notice that this is 0.59 to 2 d.p.

    Grandad
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  3. #3
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    Thanks.
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