I was just wondering what the odds are of three people at a 9 ring game having the same hole cards. Played a hand today online where the pot split 3 ways and each player held j9. I don't remember ever seeing this happen and it was right after a few suspect hands where full houses were beat by quads.
3 Answers
Unfortunately, this is the kind of probability question that would take a couple of hours and reams of paper notes to get the exact answer. But simulating it is easy (I have loads of C code for that).
I got about 1 in 500. (205423 hands out of 100000000).
This is for just 3 players on the table
First player has to be unpaired
94%
Second player has nine ways to match
0.73%
Third player has four ways to match
0.35%
Total
0.0025% = 1 / 40782
I think you would multiple by combin(9,3) = 84
And this is pretty close the the simulation from Lee 1 / 485.5
i ran a histogram on the number of different hands in a 9 player game. this is very preliminary, but i got the results:
1000000 5.0<=8.833096/1000000<=9.0 0,[0,0,0,0,0,3,212,9030,148196,842559],0 NaNs: 0
so 84% of the time all the hands are different. 15% of the time two hands are alike. 1% of the time 3 hands are alike or two sets of players have the same hand or some other combination reduced the number of different hands.
edit: larger sample:
1000000000 4.0<=8.833342/1000000000<=9.0 0,[0,0,0,0,4,2238,220758,8874325,148238607,842664068],0 NaNs: 0
Ax
variation, so it can't be that uncommon. This variation seems more useful than try to find the exact hole cards.