2. Questions Bank
  3. 11th Class
  4. Mental Ability
  5. Permutations and Combinations

11th Class Mental Ability Permutations and Combinations Question Bank Question - Permutation and Combination

  • question_answer
    How many numbers of 5 digits can be formed with the digits 0, 2, 3, 4 and 5 if the digits may repeat?

    A) 2500

    B) 250

    C) 120

    D) 2400

    E) None of these

    Correct Answer: A

    Solution :

    Explanation Option (a) is correct. Ten thousands place can assume only non-zero digits hence ten thousands place can be filled up in 4 ways and thousands place can be filled up in 5 ways since repetition is allowed (and 0 can be filled up in this place). Similarly hundreds, tens and unit places can be filled up in 5 ways each. \[\therefore \] The required number of numbers \[=4\times 5\times 5\times 5\times 5=2500\]


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