Help Basic Probabilities

[Reflection46n2]

I consider myself a relative beginner to texas hold'em as a college student but i am having trouble understanding how say with 47 unseen cards and 9 to help me (flush draw) how i will win 35% of the time. Is this done using random variables? (in)depenent events? Standard deviations? i cant seem to find a true explanation of this. Any info or links are greatly appreciated.

[asdf1234]

You just calculate the probability of missing it. For example, if you have the flush draw you mentioned, there are 47 unseen cards and nine help you. So, there are 38 out of 47 cards that miss it for you. Then on the river, there are 37 out of 46 cards that miss it for you.

(38/47) * (37/46) = probability of not making flush
1- (38/47)*(37/46) = probability of making flush

[SossMan]

Just as a side note,
35% is the chance that at least one flush card will get there. Thats it. This doesn't mean you will win 35% of the time since some of the time the flush card will pair the board, or someone may have a higher flush (or st8 flush).