if you want to practice combinatorics: omaha question

[mosta]

so I can do basic combinatorics, but my level (or lack) of talent is that I often befuddle myself for a while before I set the problem up right. this one isn't hard, but I started it the wrong way a couple times. so for anyone who wants to practice, let me ask what you get and then I'll show my answers to check myself.

the question, in several parts (idea is that you're playing omaha--what is the chance someone else has a suited ace).

omaha. 10 players. all 10 see the flop for simplicity. remember a hand is four cards in omaha.

1. before the flop: what is the chance someone is dealt the ace of spades?

2. before the flop: if someone gets the ace of spades as their first card, what is the chance they get at least 1 more spade?

3. on the flop: flop has 2 spades. you have no spades. assume someone has the ace. what is the chance it is suited?

4. on the flop: same as above except this time you have 2 spades yourself (KsXs). what is the chance the guy with the ace has it suited.

if anyone can come up with good questions involving more aces or anything, post and I'll try them.

disclaimer: yes these questions are a bit unrealistic, b/c you generally want to ask: what is the chance he has the suited ace,_given_ his flop action? but we can give it a bit more realism by assuming he will play the naked ace (as a bluff) the same way as the suited ace.


edit: if you know this and never screw it up, maybe try to leave in case someone else wants to try.