mr and mrs smith had invited 9 of their friend and their spouses for party at wiki beachresort.the stand for group photograph if mr smith never stand next to mrs smith then how many way group arrange in row(A)20!(B)19!+18!(C)18*19!(D)2*19!

• simplest... ans is 18*19!
  method ..: mr and mrs smith never b together so out of 20(with both them) 19 can b any place so total = 19!
  also 1 of them can stand with other so 18 places /..
  so total is 18*19!..
• 12 years agoHelpfull: Yes(46) No(7)
• 19!*18
  bcoz along with mr and mrs smith can be arranged in 19!*2 (2 bcoz of mr and mrs smith arrangement) all together can be arranged in 20! ways so no mr and mrs smith can be arranged in 20!-19!*2 =19!*18
• 12 years agoHelpfull: Yes(35) No(2)
• 20!-(19!*2)
  total possibility minus they will be together
• 12 years agoHelpfull: Yes(16) No(3)
• Total People: 20
  Number of arrangement possible: 20!
  Mr. and Ms. Smith can be together in 19!*2! cases.
  Because If they stay together we can consider two of them as a single element. So, 19! ways and they themselves can be arranged in 2! ways among themselves. so, 19!*2!.
  
  So, number of cases they will not be together is 20! - 2!*19! =20!- 2*19! = 18*19!
• 8 years agoHelpfull: Yes(2) No(0)
• total possible ways are 20!
  the no of ways in which mr and mrs smith sit together is 2*19!
  so 20!-(2*19!)=18*19!
• 9 years agoHelpfull: Yes(1) No(1)