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Thread: Circular Permutation??

  1. #1
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    Angry Circular Permutation??

    if there are 7 boys and 5 girls, how many circular arrangements are possible if the ladies do not sit adjacent to each other.??
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  2. #2
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    Seat the boys at the table.
    That can be done in $\displaystyle 6!$ ways. WHY?
    That creates seven places to place five chairs.
    So what do you think the answer is?
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  3. #3
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    Quote Originally Posted by Plato View Post
    Seat the boys at the table.
    That can be done in $\displaystyle 6!$ ways. WHY?
    That creates seven places to place five chairs.
    So what do you think the answer is?
    i think:-

    =6!*p(7,5)
    =6!*7!/(7-5)!

    ???
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  4. #4
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    Well if I were to confirm that answer, I would have no way to know what you understand about this question.

    Tell us what those numbers mean!
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  5. #5
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    Quote Originally Posted by Plato View Post
    Well if I were to confirm that answer, I would have no way to know what you understand about this question.

    Tell us what those numbers mean!
    as per your suggestion;-
    boys ways;-(7-1)=6!
    now there are 5 girls and 7 seats(in b/w boys) so there are P(7,5) number of ways, the girls can sit.
    p(7,5)=7!/(7-5)!

    i.e, total no. of ways= 6!*p(7,5)
    = 6!*7!/(7-5)!
    = 1814400 (but this ans is wrong).
    ans is = 252
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  6. #6
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    Quote Originally Posted by Plato View Post
    That answer is completely wrong!
    You need to contact your educational authority.
    That is incompetent!
    ans=252 is in my book.
    what should i do if i m doing any thing wrong with girls ways???
    and what should be the ans.??
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  7. #7
    Junior Member nimon's Avatar
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    Is it more than a coincidence that $\displaystyle \frac{15120}{60} = 252$?

    Maybe the author just miscalculated and divided by 60 somehow

    "Sorry guys, I'll fix that in Dinner Party Combinatorics V2.0"
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