Basic Prob Question - Flush Draw

[nlwolf]

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Multiply them all together, (4/17)*(2,145/19,600)*(9/47) = 77,220 / 15,660,400 = 3,861 / 783,020 = 0.5%.

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I think this is incorrect.
Its an answer to the question: "what is the probability that two-flush flop will come, my opponents has matching suited hole card and third suit comes on the turn".

But we're already on the flop and its two-suited, so the probability is: P(opponent has suited hand)*P(another suit comes on the turn)

(Note: this assumes hero doesn't have suit matching 2-suited board)
Opponent has a matching suited hand: 11/47 * 10/46 = 0.051
Another suit comes on the turn: 9/45 = 0.2

Final probability = 0.2 * 0.051 = 0.01 = 1%

In reality its a bit higher, because villain is more likely to see the flop with suited hand than offsuit (eg 53s vs 53o), but I dont think its bigger than hmm 1.5%