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Home Aptitude Permutation and Combination Comments

  • Question
  • In how many ways, can 15 people be seated around two round tables with seating capacities of 7 and 8 people?


  • Options
  • A. 15!/(8!)
  • B. 7!/88!
  • C. 15C8 x 6! x 7!
  • D. 15C8 x 8!

  • Correct Answer
  • 15C8 x 6! x 7! 

    Explanation

    Number of ways in which 8 persons can be selected from 15 persons = 15C8
    Now, 8 persons can be seated around a circular table in 7! ways.
    Now, remaining 7 persons can be seated around a circular table in 6! ways.
    ? Required number of ways = 15C8 x 7! x 6!


  • Permutation and Combination problems


    Search Results


    • 1. 
      There are 10 questions in a question paper. In how many ways, a student can solve there questions, if he solves one or more question?

    • Options
    • A. 1024
    • B. 1025
    • C. 1023
    • D. 1000
    • Discuss
    • 2. 
      Find the number of combinations that can be formed with 5 oranges, 4 mangoes and 3 bananas, when one fruit of each kind is taken.

    • Options
    • A. 60
    • B. 120
    • C. 110
    • D. 75
    • Discuss
    • 3. 
      In how many ways, 12 balls can be divided between 2 boys, one receiving 5 and the other 7 balls?

    • Options
    • A. 1784
    • B. 1584
    • C. 1854
    • D. 1560
    • Discuss
    • 4. 
      There are 10 points in a plan, out of which 5 are collinear. Find the number of straight lines formed by joining them.

    • Options
    • A. 36
    • B. 45
    • C. 30
    • D. 35
    • Discuss
    • 5. 
      Find the number of diagonals formed in hexagon .

    • Options
    • A. 12
    • B. 10
    • C. 6
    • D. 9
    • Discuss
    • 6. 
      O and A occupying end places.

    • Options
    • A. 12
    • B. 14
    • C. 20
    • D. 18
    • Discuss
    • 7. 
      E being always in the middle.

    • Options
    • A. 18 ways
    • B. 24 ways
    • C. 48 ways
    • D. 20 ways
    • Discuss
    • 8. 
      Vowels occupying odd places .

    • Options
    • A. 12 ways
    • B. 16 ways
    • C. 6 ways
    • D. 20 ways
    • Discuss
    • 9. 
      Vowels being never together.

    • Options
    • A. 36 ways
    • B. 84 ways
    • C. 120 ways
    • D. 10 ways
    • Discuss
    • 10. 
      In how many ways can the letters of the word 'Director' be arranged so that the three vowels are never together?

    • Options
    • A. 1800
    • B. 18000
    • C. 16000
    • D. 1600
    • Discuss


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