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BCECE Engineering BCECE Engineering Solved Paper-2001

  • question_answer
    In how many ways can 5 keys be put in a ring:

    A)  \[\frac{1}{2}4!\]                              

    B)  \[\frac{1}{2}5!\]                              

    C)  \[4!\]                   

    D)         \[5!\]

    Correct Answer: A

    Solution :

    Key Idea: The n keys can be put in a key ring in\[\frac{(n-1)!}{2}.\] The total number of ways that five keys can be put in a ring is \[\frac{(5-1)!}{2}=\frac{4!}{2}\] [Since in a key ring either we put clockwise or anticlockwise both will have same case]


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