Probability conundrum
 

I've got two different tables of Holdem probabilities from sites on the internet and they appear to contradict on certain situations!

For example, one has an open ended straight draw completing by the river at 34% and the other has it as 31.5%.

One has a flush draw completing as 35% whilst the other has it as 39%!

If anyone out there is ABSOLUTELY CERTAIN that they have the correct probabilities for these two scenarios I'd greatly appreciate it, as it will probably show that one of my tables is correct on both counts and the other one should not be trusted.

Thanks,

Gattaca.

The 2 lower percentages are the correct ones.
But I wouldn't bet on it!

Gattaca,

Mooee is correct. The chance of hitting an open ended straight after the flop is indeed 31.5% and the chance of hitting a flush after the flop is 35%.

Lets assume you hold 8,9 and the flop reads 2,10,J.
You need a 7 or a Q to make you straight which is 8 outs (4 7's and a Q's)
The probability of NOT getting a 7 or a Q on the turn is 39/47 and then the probability of NOT getting a 7 or Q on the river is 38/46. if we multiply these together we get 1482/2162=0.6855 which is the probability that we DONT get a 7 or a Q on the turn and river. So the probability that we DO make our straight by catching 1 of 8 cards after the flop is 1-0.6855=0.3145=31.45%

For the flush draw we would need 1 of 9 cards on the turn or river. So the probability we dont make a flush is 38/47 x 37/46 = 1406/2162 = 0.6503. Therefore the chance of making a flush after having 4 out of 5 after the flop is 34.97%

Hope this helps

Cheers
ATC

Thanks
 

Thanks, guys.

If I have any maths queries about Holdem I'll know who to ask, ATC!

Gattaca.