There is a row of 172 children of which 2 of them are girls. They are standing in an initial order such that a set of 9 boys, who are facebook addicts, stand next to each other in a certain order. Now, the positions of boys and girls are shuffled such that, the order of girls the same, the facebook addicts are together in the same order, but the position and order of remaining boys are changed. How many distinct arrangements of the students can be done (including the initial order) by preserving the order of girls and keeping the facebook addicts together. [DCRU]
A. 163 !
B. 162 !*13203
C. 163!*13203
D. 162 !

• consider 9 fb addicts as one unit as their order is not changed and are always together. consider 2 girls as one unit as their order donot change . remaining is
  172-9-2 = 161
  
  now (9fb)(2g)(161) to tal we need to arrange 163 groups
  
  therefor 163!
• 10 years agoHelpfull: Yes(17) No(2)
• so we need to keep the facebook guys together and the two girls together without changing their order so let us consider all facebook guys as one group and other two girls as another group so from 172 we need to subtract 11 members so 161 and now add these two groups 163 now total no.of arrangements are 163! we won't arrange facebook guys inside the group as the order should be the same same as the two girls also
  so ans:163!
• 10 years agoHelpfull: Yes(2) No(1)
• It is simple as letter arrangements.
  Consider 9FB addicts as 1 letter and 2 girls and other letter and now we are left with 161 different letters.
  So the solution would be (9!/9!)*(2!/2!)*163!=163!
  You will get these type of questions Permutation Chapter of R.S.Aggarwal.
• 10 years agoHelpfull: Yes(0) No(3)