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Math Help - Random variables help

  1. #1
    Super Member
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    Sep 2008
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    Random variables help

    Two coins are tossed 50 times. The number of heads is noted each time.

    a Construct a probability distribution table for the number of heads when the two coins are tossed once, assuming that the two coins are unbiased.

    b Work out how many times you would expect to get 0, 1 or 2 heads.
    a) the possible out comes are; HT, HH, TT.

    probabiltiy of getting 0 heads = 1/3

    1 heads =1/3

    2 heads = 1/3

    is this correct?
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  2. #2
    Member
    Joined
    Dec 2008
    From
    Auckland, New Zealand
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    189
    No that isn't correct...each coin toss has a 1/2 chance of being either heads or tails.

    Your outcomes and probabilities are:

    P(HH) = 1/2 * 1/2 = 1/4
    P(TT) = 1/2 * 1/2 = 1/4
    P(HT) = 1/2 * 1/2 = 1/4
    P(TH) = 1/2 * 1/2 = 1/4

    Note the last 2 probabilities are the same event P(1).

    So P(0 H) = 1/4, P(1) = 1/2 and P(2) = 1/4.
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