In G-20 meeting there were 20 people representing their own country.All the representative sat around a circular table.Find the number of ways in which we can arrange them around a circular table so that there is exactly one person between two representatives namely Manmohan and Musharraf.
option
i. 2x(17!)
ii. 2x(18!)
iii. (3!)X(18!)
iv. (17!)

• Keep aside two people manmohan, musharaff and one person to be between them.
  now remaining are 17 and plus these three as one, so 18 to be arranged in a circle. To arrange 'n' in a circular fashion no of ways are (n-1)! ways. So to arrange 18 , we get 17! ways.
  Now in blw manmohan and musharaff one place is occupied by not only one person, all can be arranged , i.e 18 arrangements in blw them since 18 members are left (excluding manmohan and musaraff).
  And now manmohan and musharaff can be replaced in 2 ways.
  So totally 17!*18*2=18!*2 ways.
• 10 years agoHelpfull: Yes(52) No(4)
• manmohan,person,musharaf are considered to be a unit. they are seated in 2 ways on a circle.then remaining 17 are seated in 17! ways arounf this unit in a circle.
  hence 2*17!
  
• 10 years agoHelpfull: Yes(7) No(7)
• _ _ _ _ _ manmohan _ _ _ _ musharaf _ _ _ _ _ _ _ _ _
  
  leaving musharaf and manmohan all other 18 are arranged in 18 blanks in 18! ways
  manmohan and musharaf in 2 ways
  total - 2x18!
• 10 years agoHelpfull: Yes(6) No(1)
• 18! *2 as considering manmohan and musaraf and the person sitting between them as 1 unit....
• 9 years agoHelpfull: Yes(2) No(0)
• (18-1)!*2 then 17!*2
• 10 years agoHelpfull: Yes(1) No(3)
• leaving musharaf and manmohan all other 18 are arranged in 18 blanks in 18! ways
  manmohan and musharaf in 2 ways
  total - 2x18!
• 9 years agoHelpfull: Yes(0) No(0)
• think lyk this
  fix manmohan and mussaraf and rotate the cycle including the perosn between them so tota is 18+1 pple so circular arranfement is (19-1)!=18!
  now manmohan and mussaraf can swap their positio so 18!*2
• 9 years agoHelpfull: Yes(0) No(0)
• select one person to be placed between Manmohan and Musharraf in 18c1 way then this person and
  Manmohan and Musharraf combine as a single unit hence
  total become this one unit and remaining 17 person hence total to be arrange is 18 as we have to arrange in circular manner hence toatal arrangement (18-1)!*2( 2 for arrangement of manmohan and Musharraf among them)
  hence ans =18c1*17!*2=18!*2
  
• 9 years agoHelpfull: Yes(0) No(0)