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

  • question_answer
    How many numbers divisible by 5 and lying between 3000 and 4000 can be formed from the digits 1, 2, 3, 4, 5, 6 (repetition is not allowed)

    A) \[\frac{n+r-1}{r}\]

    B) \[^{5}{{P}_{2}}\]

    C) \[^{4}{{P}_{2}}\]

    D) \[^{6}{{P}_{3}}\]

    Correct Answer: C

    Solution :

    To be divisible by 5, the digit 5 must be at unit place, so now to be between 3000 and 4000, 3 must be at thousand place. Hence the required number of ways\[={{\,}^{4}}{{P}_{2}}\].

You need to login to perform this action.
You will be redirected in 3 sec spinner