Need help with some flop probability calcs

Megenoita · #1 12-12-2005, 03:10 PM

Hi guys,

Trying to do some work here...

how do I calculate how often JT flops a straight? I have the answer; I'm wondering HOW.

Thanks,
M

pzhon · #2 12-12-2005, 03:17 PM

There are 50 choose 3 = 50*49*48/(3*2*1) = 19600 flops. You can flop a straight that is ace-high, king-high, queen-high, or jack-high. For each possible straight, there are 4 choices for the suit of each card, except that you should subtract off the straight flush. So, the total number of flopped straights is 4*(4*4*4-1) = 252. The probability of flopping a straight is 252/19600.

Megenoita · #3 12-12-2005, 03:39 PM

Thanks...I'm going to work on this...

Megenoita · #4 12-12-2005, 03:45 PM

Okay, so I did this calculation correctly except I divided by 117600 total flops. Why exactly do we divide by 6? It's b/c of the permutations (?), right? The number of ways the same flop can come on the board?

Also, the sheet I was given said that a connector like JT flops a straight .31% of the time, not over 1% which you said. Is that sheet just wrong?

Thanks,
M

pzhon · #5 12-12-2005, 04:48 PM

[ QUOTE ]
Okay, so I did this calculation correctly except I divided by 117600 total flops. Why exactly do we divide by 6? It's b/c of the permutations (?), right? The number of ways the same flop can come on the board?

[/ QUOTE ]
Yes. It's important to be consistent. If you distinguish between A[img]/images/graemlins/spade.gif[/img] K[img]/images/graemlins/spade.gif[/img] Q[img]/images/graemlins/spade.gif[/img] and K[img]/images/graemlins/spade.gif[/img] Q[img]/images/graemlins/spade.gif[/img] A[img]/images/graemlins/spade.gif[/img], then you have 6 times as many flops, and 6 times as many straights as I calculated. The ratio will be the same.

[ QUOTE ]

Also, the sheet I was given said that a connector like JT flops a straight .31% of the time, not over 1% which you said. Is that sheet just wrong?

[/ QUOTE ]
That sheet is wrong. In this table, Mike Caro confirms that the probability of getting a particular straight is about 0.33%, and that QJo flops a straight 0.98% of the time. QJo only has 3 possible flopped straights as opposed to 4 for JT.

Perhaps you are looking at data that was caclulated for AKs, though that should be 0.32%.

Megenoita · #6 12-12-2005, 09:29 PM

If you don't mind, P, then how do we do the problem of KQ flopping a pair? I know it's about 16% each or 32% total.

The way I was doing it was apparently wrong but I somehow came to the right answer...how do you do this?

Thanks,
M

Megenoita · #7 12-13-2005, 12:27 AM

bump-anyone?