The most important thing is how you manage you loss and wining, rather the probability of wining each trade as it's not a parameter that you can control. Yet, you focus on talking of probability of wining each trade which is beyond anybody's comprehension. If you really want to talk about it, combine it with % of loss or wining that you will accept in each trade and calculate the expected wining (or loss) for a number of trades you will conduct. Say you start with 10k of capital and impose a trading strategy of cut loss at 10% and taking profit at 10%. So in first trade your expected wining is .8*1000-0.2*1000=$600. And then you can add $600 expected gain to you capital to conduct another trade or go back to 10k to conduct second trade and so on. This is also called decision theory.
Don't talk like you know the theory of probabality while nobody else does here as there are plenty of vigrously trained statisticians here on this board. So keep low profile please!
