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Thread: Probability

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    Probability

    If the numerals 2,3,4,5,6 are randomly arranged to make a 5 digit number, what is the probability the number is:

    a) an odd number less than 30000

    b) an even number greater than 40000

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    Taking a break! dan964's Avatar
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    Re: Probability

    I won't do the computation but:
    (A) Pick the first digit to be 2, and then pick the last digit to be either 3 or 5, out of the remaining 4 digits.

    (B) Pick the first digit to be either 4 or 5 or 6. And then from the remaining collection:

    If 4 is the first digit, then you can pick 2 or 6 for the last digit out of the remaining 4
    If 5 is the first digit, then you can pick 2 or 4 or 6 for the last digit.
    If 6 is the first digit, then you can pick 2 or 4 for the last digit.

    Expected Answers:
    (A)
    0.2*0.5 = 0.1

    (B)
    0.2*0.5+0.2*0.75+0.2*0.5
    = 0.35

    (show why.)

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