- Messages
- 98
- Reaction score
- 86
- Points
- 28
the answer is right......but can you plz explain it.....
thanx
Assume we have B1 B2 B3 B4 B5 and G1 G2 G3 (They are all different people, hence the numbering )
We want the boys to sit together. As a result we have to group them as a single entity.
Now we have B1B2B3B4B5 as a group.
In the group, there are 5! ways in which they can be arranged, whether B1 is first followed by B2, or B2 is first followed by B1 and so on.
It is time to put this group amongst the girls.
We can have an arrangement of:
G1 [the boys group] G2 G3
Or,
[the boys group] G1 G2 G3
Or,
G2 [the boys group] G1 G3
And so on.
You should now notice that we have 4 different items to "play" with, hence 4!
Therefore 4! * 5!