re: Poker & Calculating set odds
Assumptions: Your opponent does not hold any of your set card (if you have pocket 2's, and he's raised preflop, that's a pretty fair assumption).
With this assumption, the odds of a set not flopping are (46/48)*(45/47)*(44/46) = 0.9583*0.9574*0.9565 = 87.7% chance that you won't flop a set. And thus your chances of flopping a set (or quads) is 12.3%, or 1:7.13 or 1 out of 8. However you prefer expressing probability. If you don't make the assumption that the raiser has 2 cards that aren't a 2, you get 11.8%, but essentially the same number.