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?

• 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
• 11 years agoHelpfull: Yes(30) No(4)
• 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!
• 11 years agoHelpfull: Yes(6) No(5)
• 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!.
• 11 years agoHelpfull: Yes(5) No(2)
• 18!*2!*18c1
• 11 years agoHelpfull: Yes(5) No(1)
• 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
• 11 years agoHelpfull: Yes(2) No(3)
• 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
• 11 years agoHelpfull: Yes(1) No(2)
• 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!
• 10 years agoHelpfull: Yes(0) No(2)
• 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
• 6 years agoHelpfull: Yes(0) No(0)