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Math Help - basic prob. questions

  1. #1
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    basic prob. questions

    A box contains 24 yellow, 25 green and 27 red jelly beans.
    If 15 jelly beans are selected at random, what is the probability that:
    a) 5 are yellow?
    b) 5 are yellow and 9 are green?
    c) At least one is yellow?


    I'm unsure of the techniques needed for these, any suggestions are welcome.
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  2. #2
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    Jelly beans probability question

    A box contains 25 yellow, 27 green and 29 red jelly beans.
    If 10 jelly beans are selected at random, what is the probability that:

    6 are yellow?

    6 are yellow and 3 are green?

    At least one is yellow?
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  3. #3
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    Quote Originally Posted by APOC197777 View Post
    A box contains 25 yellow, 27 green and 29 red jelly beans.
    If 10 jelly beans are selected at random, what is the probability that:
    6 are yellow?
    6 are yellow and 3 are green?
    At least one is yellow?
    There are \binom{81}{10} ways to select these ten jelly beans.
    There are \binom{25}{6}\binom{56}{4} ways to select exactly 6 are yellow jelly beans..

    Can you finish?
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  4. #4
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    Quote Originally Posted by jimmyp View Post
    A box contains 24 yellow, 25 green and 27 red jelly beans.
    If 15 jelly beans are selected at random, what is the probability that:
    a) 5 are yellow?
    b) 5 are yellow and 9 are green?
    c) At least one is yellow?


    I'm unsure of the techniques needed for these, any suggestions are welcome.
    a) \frac{{24 \choose 5} \cdot {52 \choose 10}}{{76 \choose 15}}

    b) \frac{{24 \choose 5} \cdot {25 \choose 9} \cdot {27 \choose 1}}{{76 \choose 15}}

    c) 1 - Pr(none are yellow).
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