JEE Main & Advanced Mathematics Permutations and Combinations Question Bank Critical Thinking Questions

  • question_answer 12 persons are to be arranged to a round table. If two particular persons among them are not to be side by side, the total number of arrangements is [EAMCET 1994]

    A) \[9(10\ !)\]

    B) \[2(10\ !)\]

    C) \[45(8\ !)\]

    D) \[10\ !\]

    Correct Answer: A

    Solution :

    12 persons can be seated around a round table in \[11\ !\] ways. The total number of ways in which 2 particular persons sit side by side is\[10\ !\ \times \ 2\ !\]. Hence the required number of arrangements\[=11\ !\ -10\ !\ \times 2\ !\ =9\times 10\ !\].


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