Elitmus
Exam
Numerical Ability
Permutation and Combination
In How many ways can 12 papers be arranged if the best and the worst papers never come together?
Read Solution (Total 7)
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- assume two particular paper as one paper,so total number of ways to arrenge this=(12-1)!=11!,now these two paper can be arrenged in 2 ways......without any restriction paper can be arrenged in 12! ways.
so number ways is=12!-2.11!=10.11!ways
- 10 years agoHelpfull: Yes(82) No(2)
- firstly we find how many all arrangement r possible of 12 papers ie=12!
now when best n worst papr always comes together ie=11!*2!
then when best n worst papr r never comes together=all arrangement-worst n best always comes together
=12!-11!2!
=399168000 - 10 years agoHelpfull: Yes(22) No(1)
- 12!-(11!*2!)
- 10 years agoHelpfull: Yes(8) No(0)
- First of arrange 12 papers 12! No. Of ways equals 12!-2*11!
- 10 years agoHelpfull: Yes(2) No(0)
- here are 5 letters and five addressed envelopes. the number of ways in which all the letters can be put in wrong envelopes is
Total Number of ways = 5! = 120
The formula for the derangement can be used directly. The number of derangements is
n! (1/2!−1/3!+1/4!+…+(−1)ⁿ/n!)
Here n = 5
5 ! ( 1/2! - 1/3! + 1/4! - 1/5!)
= 120 ( 1/2 - 1/6 + 1/24 - 1/120)
= 60 - 20 + 5 - 1
= 65 - 21
= 44
So probabilty = 44/120 - 5 years agoHelpfull: Yes(1) No(0)
- First assume two papers as one paper... So that remaining papers arranged in 11! Ways . And two papers so, 11!*2
So , we have 13 spaces between 12 papers so, the two papers arranged in 12! Ways ... So finally we can arrange that 2 papers in
12!-11!*2 - 9 years agoHelpfull: Yes(0) No(1)
- all arrangements - arrangements with best and worst paper together=12! -2! * 11!
- 9 years agoHelpfull: Yes(0) No(1)
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