Latest TCS Aptitude Question SOLUTION: there are 20 people with 2 sisters among them.They are arranged in circular manner.how many ways they can be arranged such that there is always a member b/w two sisters?

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there are 20 people with 2 sisters among them.They are arranged in circular manner.how many ways they can be arranged such that there is always a member b/w two sisters?

Asked In TCS (10 years ago)

Unsolved Read Solution (8)

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Read Solution (8) :

sandeep gantait  (10 years ago)

consider there is a guy between two sisters :18C1 ways
2 sisters can be arranged in 2! ways
total circular arrangement would be:(18-1)!
total:17!x2!x18

Is this solution Helpfull? Yes (30) | No (4)  

rajesh  (10 years ago)

consider two sisters and a boy b/w them as one unit.and 17 people as 1 unit so total 18 units can be arranged in (18-1)!.
two sisters can be arranged in 2! ways.
Total = (17!)*2!

Is this solution Helpfull? Yes (6) | No (5)  

Sunny Agarwal  (10 years ago)

There are 18 boys and 2 girls at first fix a boy in a particular place and then there are 18 spaces among which two girls are to be arranged i.e. 18P2 and the rest of the boys can be arranged in 17! ways. So the answer is, 18P2 * 17!.

Is this solution Helpfull? Yes (5) | No (2)  

vinit  (10 years ago)

18!*2!*18c1

Is this solution Helpfull? Yes (5) | No (1)  

Awantika singh  (10 years ago)

18!*2!
3 people(2sis n a member)are taken as 1 unit so total people 18.they can be arrange in 18! ways.Now for 2! two sisters van arrange themselve in 2 ways

Is this solution Helpfull? Yes (2) | No (3)  

SHAIK SADDAM HUSSAIN  (10 years ago)

n people can be arranged in (n-1)! ways in circular fashion,
2 sisters there and a boy in between so we can take them as a single piece,so totally 18,
they can be arranged in (18-1)! ways in round fashion,
two sisters can be arranged in 2 ways
finally we can arrange them in 17!*2=711374856192000

Is this solution Helpfull? Yes (1) | No (2)  

Sri Reddy  (10 years ago)

there r 2 sisters...20-2=18
18 can be seated in 18-1=17!ways
now between 18 people there r 18 gaps...
in this 18 gaps the 2 sisters can be seated in 18c2*2
so the final answer is 17!*18c2*2!

Is this solution Helpfull? Yes | No (2)  

prashant  (5 years ago)

2 sisters + 1 member can be considered as 1 unit now possible arrangements=17!
2 sisters can be arranged in = 2!
1 member can be selected in = 18c1 ways
total ways=17!*2!*18c1

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