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  • Question
  • A library has 'a' copies of one book, 'b' copies of each of two book, 'c' copies of each of three books and single copy of 'd' book. The number of ways in which these books can be distribute is?


  • Options
  • A. (a + b + c + d)! / (a! b! c!)
  • B. (a + 2b + 3c + d)! / {a! (b!)2 (c!)3}
  • C. (a + 2b + 3c + d )! / (a! b! c!)
  • D. None of these

  • Correct Answer
  • (a + 2b + 3c + d)! / {a! (b!)2 (c!)3} 

    Explanation

    Total number of books = a + 2b + 3c + d . Since there are 'b' copies of each of two books, 'c' copies of each of three books and single copy of 'd' book.
    Therefore, the total number of arrangements is = (a + 2b + 3c + d )! / {a! (b!)2 (c!)3}


  • More questions

    • 1. 
      In a race of 600 m, A can beat B by 60 m and in a race of 500 m, B can beat C by 50 m. By how many meters will A beat C in a race of 400 m?

    • Options
    • A. 364 m
    • B. 254 m
    • C. 324 m
    • D. 354 m
    • Discuss
    • 2. 
      36.98276421 x 21.00002 =?

    • Options
    • A. 775
    • B. 785
    • C. 800
    • D. 805
    • Discuss
    • 3. 
      In the figure, BD and CD are angle bisectors of ? ABC and ? ACE, respectively. Then ? BDC is equal to :

    • Options
    • A. ?BAC
    • B. 2?BAC
    • C. 1 ?BAC 2
    • D. 1 ?BAC 3
    • Discuss
    • 4. What is the unit digit in {(6374)1793 x (625)317 x (341491)}?

    • Options
    • A. 0 
    • B. 2
    • C. 3
    • D. 5
    • Discuss
    • 5. How many seconds will a 500 metre long train take to cross a man walking with a speed of 3 km/hr in the direction of the moving train if the speed of the train is 63 km/hr?

    • Options
    • A. 25
    • B. 30
    • C. 40
    • D. 45
    • Discuss
    • 6. Two, trains, one from Howrah to Patna and the other from Patna to Howrah, start simultaneously. After they meet, the trains reach their destinations after 9 hours and 16 hours respectively. The ratio of their speeds is:

    • Options
    • A. 2 : 3
    • B. 4 : 3
    • C. 6 : 7
    • D. 9 : 16
    • Discuss
    • 7. A train travelling at a speed of 75 mph enters a tunnel 3½ miles long. The train is ¼ mile long. How long does it take for the train to pass through the tunnel from the moment the front enters to the moment the rear emerges?

    • Options
    • A. 2.5 min
    • B. 3 min
    • C. 3.2 min
    • D. 3.5 min
    • Discuss
    • 8. Which one of the following numbers is completely divisible by 45?

    • Options
    • A. 181560
    • B. 331145
    • C. 202860
    • D. 2033555
    • E. None of these
    • Discuss
    • 9. 7589 -? = 3434

    • Options
    • A. 4242
    • B. 4155
    • C. 1123
    • D. 11023
    • E. None of these
    • Discuss
    • 10. 
      Find the angle between minute hand hour hand at 11 : 50 AM

    • Options
    • A. 55°
    • B. 22.5°
    • C. 15°
    • D. None of these
    • Discuss


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