📢 Too many exams? Don’t know which one suits you best? Book Your Free Expert 👉 call Now!


    âš¡ Azaadi sale - Celebrate Independence Day with Flat 55% Off On all courses! 13 to 17 Aug âš¡ Enroll Now

    Question

    How many different nine digit numbers can be formed

    from the number 66 55 99 222 by rearranging its digits so that the odd digits occupy even positions only?
    A 70 Correct Answer Incorrect Answer
    B 1040 Correct Answer Incorrect Answer
    C 120 Correct Answer Incorrect Answer
    D 720 Correct Answer Incorrect Answer
    E 60 Correct Answer Incorrect Answer

    Solution

    Number of even places = 4 Number of even digits = 5 (6,6,2,2,2) Number of odd places = 5 Number of odd digits = 4 (5,5,9,9) Since 5 & 9 are repeated two times odd  digits can be arranged in 4!/(2!×2! )  = 6 ways Since 6 is repeated two times & 2 is repeated three times  even digits can be arranged in  5!/(2! ×3!)  = 10 ways Hence, the required number of ways = 6 × 10 = 60 ways.

    Practice Next
    More Permutation and combination Questions
    ask-question

    Not sure which exam is best for you Talk to our expert

    Get My Free Call