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JEE Main & Advanced Mathematics Permutations and Combinations Question Bank Definition of permutation, Number of permutations with or without repetition, Conditional permutations

  • question_answer
    Six identical coins are arranged in a row. The number of ways in which the number of tails is equal to the number of heads is

    A) 20

    B) 9

    C) 120

    D) 40

    Correct Answer: A

    Solution :

    Required number of ways\[=\frac{6\ !}{3\ !\ 3\ !}=\frac{720}{6\times 6}=20\]. [No. of heads\[=3\], no. of tails =3 and coins are identical]


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