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08-07-2003, 03:55 PM
I suck at math... I can't figure out all the probabilities while playing. Is there a basic cheat sheet/frequently used probablities list?
Example:
Getting your 5th Flush card on Turn/River.
Making your open-ended straight on River.
Making you belly-buster straight on turn/river.
Catching a FH from your 2 pair with Turn/river to come.
Etc...

Is there a list of frequently used probabilites on this site?

asdf1234
08-07-2003, 08:07 PM
It's pretty easy to calculate these once you get the algorithm down.

Let's say that you're holding two hearts and two more hearts come on the flop. You've got nine outs to improve. You have to calculate this with two cards to come by figuring out your chance of not improving and then subtracting that from one.

So, 47 unknown cards in the deck, 9 of which help, 38 of which don't. Therefore, your chances of missing on both the turn and river are (38/47)*(37/46) = .6503237

That is the probability of missing, so the probability of hitting is 1 - .6503237 = .3496762

If you want to convert this to odds, just take .6503/.3497 = 1.86. Your odds of hitting are 1.86:1 against.

There's a decent discussion of hold 'em arithmetic in More Hold 'Em Excellence by Lou Krieger. Of course you could also pick up a probability/stats book.

That being said,
(all with two cards to come)
Open ended straight: 2.2:1
Gutshot straight : 5.1:1
Boat with two pair : 5.1:1
Flush : 1.86:1

You can calculate the other ones with the method I outlined above. Hope this helps.

ccwhoelse?
08-08-2003, 12:23 AM
(38/47)*(37/46) = .6503237

how come you can't do
(9/47)*(9/46)
it's pretty obvious but still, hehe.

Wake up CALL
08-08-2003, 11:13 AM
[ QUOTE ]
(38/47)*(37/46) = .6503237

how come you can't do
(9/47)*(9/46)
it's pretty obvious but still, hehe.

[/ QUOTE ]

Here is a good reason, because it gives you an incorrect answer.

Styles
08-08-2003, 02:07 PM
It's in both 2+2 HE Books.
HPFAP.Page 309.Appendix A.Probability of Completing Hand
HEP.Page 106-107.Probability Introduction

M.B.E.
08-08-2003, 07:11 PM
There are a couple of small errors in the chart:

http://forumserver.twoplustwo.com/showflat.php?Cat=&amp;Board=books&amp;Number=159386

M.B.E.
08-08-2003, 07:18 PM
[ QUOTE ]
Is there a list of frequently used probabilites on this site?

[/ QUOTE ]

Yes:

Post by Dynasty giving useful odds for holdem (http://forumserver.twoplustwo.com/showthreaded.php?Cat=&amp;Number=44374)