Examveda
Examveda

In how many ways can 10 examination papers be arranged so that the best and the worst papers never come together?

A. 8 × 9!

B. 8 × 8!

C. 7 × 9!

D. 9 × 8!

Answer: Option A

Solution(By Examveda Team)

No. of ways in which 10 paper can arranged is 10! Ways.
When the best and the worst papers come together, regarding the two as one paper, we have only 9 papers.
These 9 papers can be arranged in 9! Ways.
And two papers can be arranged themselves in 2! Ways.
No. of arrangement when best and worst paper do not come together,
= 10! - 9! × 2!
= 9!(10 - 2)
= 8 × 9!

Join The Discussion

Comments ( 12 )

  1. Ravi Sudani
    Ravi Sudani :
    2 years ago

    👌👌👌👌👌 Tysm for Help.
    Special thanks to Kumar chandan

  2. Meenal Bhojwani
    Meenal Bhojwani :
    3 years ago

    it was really helpful

  3. Convenience Chibatamoto
    Convenience Chibatamoto :
    3 years ago

    Waal...you are really smart!

  4. Convenience Chibatamoto
    Convenience Chibatamoto :
    3 years ago

    Waal...you are really smart!

  5. Manish Jha
    Manish Jha :
    4 years ago

    10!-9!.2! Solve as below
    10.9!- 9!.2! And 9! take common here then we get 9!- (10-2 )=8.9!

  6. Karan Rohilla
    Karan Rohilla :
    5 years ago

    10!-9!.2!
    We can also write
    (10*9!-9!*2!)
    And 9! Is taken out, ie. We get
    9!(10-2)= 9!*8

  7. Kumar Chandan
    Kumar Chandan :
    5 years ago

    See, the question, there have been give that best and worst papers never come together.
    In the second step of the solution, best and worst paper have been taken together means,
    best + worst = One new type of paper.
    And the total examination paper is 10 and when best and worst paper taken together it become (10 -1) i.e. 9.
    And these 9 papers can be arranged themselves into 9! ways.

  8. Hema
    Hema :
    5 years ago

    I have a doubt how the 9! came in the answer

  9. Kumar Chandan
    Kumar Chandan :
    5 years ago

    Where is your problem? @Gautam and what is the problem that you are facing in question?

  10. Gautam
    Gautam :
    5 years ago

    Still M not getting it.!!

  11. Sourav
    Sourav :
    5 years ago

    In the second step,why the best and worst paper have been taken together?

  12. Rajat Tiwari
    Rajat Tiwari :
    5 years ago

    how to solve 10!-9!.2!

Related Questions on Permutation and Combination