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Math Help - 10 Balls probability

  1. #1
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    10 Balls probability

    10 Balls probability-1.png
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  2. #2
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    Re: 10 Balls probability

    Initially half of the balls are odd. The first ball being odd has a probability of 1/2. Taking one odd ball out leaves 4 odd and 5 even left in the bag, what is the probability of taking an odd ball out now? How do you combine the probabilities of two different events?
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  3. #3
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    Re: 10 Balls probability

    Hello, mathewnaren!

    Another approach . . .


    Ten balls numbered 0, 1, 2, ... , 9 are in a box, and two balls are taken at random.
    The probability that both numbers are odd is equal to:

    . . (A)\;\tfrac{1}{3}\qquad(B)\;\tfrac{1}{9} \qquad (C)\;\tfrac{4}{9}\qquad(D)\;\tfrac{2}{9} \qquad (E) \;1

    There are: _{10}C_2 \,=\,45 possible outcomes.

    There are: _5C_2 \,=\,10 ways to get two odd numbers.

    Therefore . . .

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