

InterviewSolution
Saved Bookmarks
1. |
Consider 21 different pearls on a necklace. How many ways can the pearls be placed in on this necklace such that 3 specific pearls always remain together? |
Answer» After fixing the places of three pearls, treating 3 specific pearsl=1 units. So , we have now 18 pearls+1 unit=19 and the number of arrangement will be (19-1)!=18! also, number of ways of 3 pearls can be arranged between themselves is 3!=6. since, there is no distinction between the clockwise and anti-clockwise arrangement. So, the required number of arrangements`=(1)/(2)18!*6(18!)` |
|