Question

3 individuals take the elevator in 15-story building. What are the odds they all will get off on the same floor? Notice: they are all strangers to one another.

Answer 1

1/15??

Answer 2

I'd say it is like this: suppose they they leave the elevator one by one.
For the first person, it doesn't matter where he or she leaves.
For the second one, there is a 1/15 chance that he/she also leaves.
The third one: also 1/15.
To have them both leave at the same story: 1/15 * 1/15 = 1/225.