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    Combinations-Number of choices

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    1. Joey is having a party. He has 10 friends, but his mom told him he could only invite 6 of them. How many choices are there if
    a. there are no restrictions
    b. there are 2 brothers who will only attend if they can attend together
    c. there are 2 girls who each will not attend if the other one does

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    https://brainmass.com/math/combinatorics/combinations-number-choices-32738

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    a) there are no restrictions
    Total no friends= 10
    If there are no restrictions then the no of choices = no of ways of choosing 6 out of 10 =
    10 C 6 = (10 x 9 x 8 x 7 x 6 x 5 ) / ( 1 x 2 x 3 x 4 x 5 x 6 ) = 210

    Answer : 210

    b ) there are 2 brothers who will only attend if they can attend together

    There are 2 cases here:

    Case 1 ) Both brothers attend
    In this case there are 4 more friends to ...

    Solution Summary

    The expert calculates the number of choices.

    $2.19

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