[Keefelane66]

First prize can go to any 1 of the 15 participants, So 15 choices.

2nd prize can then go to 1 out of the remaining 14.

And 3rd can go to any one of the remaining 13.

So number of ways we can do this is 15*14*13

3*5*2*7*13

3*10*91

2730 ways.