open ended str8 draw

Does anyone know if drawing for an open ended straight draw is profitable in long run, when there ia a flush draw on board, and u are certain that someone is drawing for the flush.

Well, you would want the probability of hitting your straight with no flush cards coming. Given that you KNOW someone is drawing to a flush (therefore has 2 of that suit) there are nine cards of the flush suit left and 36 non-flush cards. You have 6 non-flush suit cards with which to make your straight. So there are 6*35 two card combinations which make the straight and not the flush. There are 45C2 =990 total 2 card combinations left. So you will make your straight with no flush about 21% of the time, or you are about a 3.7:1 dog to make straight without flush coming. Note: this does not take into account the board pairing and being up against a full house, or one of your straight cards being counterfeited and losing to a higher straight.

I think the way I did my calc. in previous problem counts a few of the hands twice (those with both cards coming from the 6 which give you a clean straight). To resolve this, I think I need to further break down remaining deck. 30 cards neither making straight or flush, 9 cards making flush (including suited cards that make your straight), 6 cards making only straight.


So there should be 6*30 = 180 combinations of one straight and one non-straight non-flush cards, 6C2 = 15 combinations of two straight cards. So probability of straight no flush is

(180 + 15)/990 = 19.6% or about 4:1 against. Sorry for any confusion.

I assume you are talking about Stud 8 (hilo game). In stud8: straight draws are essentially worthless unless have a good low draw associated with the straight draw. Top stud8 players probably don't get involved with high straight draws unless it is (for some reason)somewhat accidential. For example: you are delt (9s 9h) 9d trip nines and then the next three cards are ten, jack, queen. There has to be some big advantage over your opponent(s) to get involved in a straight draw -- especially a high straight draw. The odds gotta be right....