Quote:
Originally Posted by Dynasty
do you know the exact odds of getting three offsuit cards Ace to Six?
I should be able to figure that for you.
First let's not immediately worry about suits. There are 10+6+3+1=20 possible three rank groupings that include exactly three ranks chosen from the six ranks A, 2, 3, 4, 5, and 6.
(If we exclude sixes, there are 6+3+1=10 possible three rank groupings that include exactly three ranks chosen from the five ranks A, 2, 3, 4, 5).
Then for each of these three rank groupings, there are ten possibilities, with five cards total, as follows for A23.
AAA23
A2223
A2333
AA223
AA233
A2233
AA23X, where X is anything other than A, 2, or 3.
A223X
A233X
A23XY where Y is anything other than A, 2, or 3.
Then there are a different number of ways each of first six these can be dealt.
hand | method | # ways |
---|
AAA23 | 4*4*4 | 64 |
A2223 | ^^ | 64 |
A2333 | ^^ | 64 |
AA223 | 6*6*4 | 144 |
AA233 | ^^ | 144 |
A2233 | ^^ | 144 |
total | . | 624 |
That's going to be the same for each three rank grouping chosen.
The next part is kind of a bitch. The problem with X and Y is they can be cards belonging to ranks 4, 5, and 6. And that causes duplications.
The problem is greatly simplified if we take your "three offsuit cards Ace to Six" to mean there cannot be four or five cards ace to six.
In other words, if we choose X and Y to be anything other than A, 2, 3, 4, 5, or 6, the solution is much easier.
hand | method | # ways |
---|
AAA23 | 4*4*4 | 64 |
A2223 | ^^ | 64 |
A2333 | ^^ | 64 |
AA223 | 6*6*4 | 144 |
AA233 | ^^ | 144 |
A2233 | ^^ | 144 |
AA23X | 6*4*4*28 | 2,688 |
A223X | ^^ | 2,688 |
A233X | ^^ | 2,688 |
A23XY | 4*4*4*28*27/2 | 24,192 |
total | . | 32,880 |
That's out of 2,598,960 possible hands. But remember there were 20 different groupings consisting of exactly three low ranks.
So the probability, if we don't worry about having all three low ranks the same suit, is 20*32,880/2,598,960=0.25302429, about one time in 4 (or odds of 3 to 1 against). That does not include four low rank or five low rank groupings. We'd have to calculate them separately. (We could do that, but you didn't ask for it).
But that's also without consideration of all three low ranks being the same suit. To correct for same suitedness, we only have to be concerned about the A23XY term (because where there's a pair, there can't possibly be such a grouping that we can't choose more than one suit).
So in other words, we have to modify the last term, the A23XY, to account for A, 2, and 3 all being the same suit. That's actually very easy.
There are 4*4*4=64 ways to chose an ace, deuce, and trey. Of these, only 4 have all three cards the same suit. Thus there are 60 ways to choose three specified low ranks without having all three cards the same suit.
Thus
A23XY | 4*4*4*28*27/2 | 24,192 |
subtracting concerns about the ace, deuce and trey being the same suit, becomes
And the completed table, corrected for suitedness becomes
hand | method | # ways |
---|
AAA23 | 4*4*4 | 64 |
A2223 | ^^ | 64 |
A2333 | ^^ | 64 |
AA223 | 6*6*4 | 144 |
AA233 | ^^ | 144 |
A2233 | ^^ | 144 |
AA23X | 6*4*4*28 | 2,688 |
A223X | ^^ | 2,688 |
A233X | ^^ | 2,688 |
A23XY | 60*28*27/2 | 22,680 |
total | . | 31,368 |
The probability is 20*31,368/2,598,960=0.24138886, or still about one in four, or still odds of about 3 to 1 against. (Consideration of all three low ranked cards being of the same suit doesn't amount to much).
That's what you asked for, Dynasty. But maybe what you really want is how often anyone will be dealt a hand with three, four, or five different low ranks, not all of the same suit. If that's really what you want, Dynasty, I'll make a separate tabulation for four different ranks and another for five different ranks. (I think that's the approach to use).
(I remember doing that years ago for various lows in Omaha-8).
Buzz