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Math Help - permutation and combination question...please help!

  1. #1
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    permutation and combination question...please help!

    5 prefects are to be chosen from 6 boys and 4 girls.in how many ways can this be done if

    a)all the prefects are boys

    b)there are at least two girls
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  2. #2
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    Quote Originally Posted by cantcount View Post
    5 prefects are to be chosen from 6 boys and 4 girls.in how many ways can this be done if
    a)all the prefects are boys
    How many ways can 5 boys be chosen from 6?.

    b)there are at least two girls
    At least two means 2 up to 4 girls are to be chosen. Add the 3 cases up.

    2 girls and 3 boys, 3 girls and 2 boys, 4 girls and 1 boy.

    \binom{4}{2}\binom{6}{3}+\binom{4}{3}\binom{6}{2}+  \binom{4}{4}\binom{6}{1}
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