The general rule I always use is: a runner-runner draw (flush or straight) is worth 1 extra out, or c. 4%.

I've read before that a runner-runner flush draw is worth more, some say 1.5 outs, or 6%.

Is a flush really 50% more likely to hit as a straight?

Granted 2% doesn't matter much, but i just want to know why. The way i figure it, flush draw you need any of 10/48 cards to make a 4 flush, and then any of 9/47 to make the flush...

10/48 * 9/47 which is very close to 4%.

Assuming you have a 3 straight, to hit a straight you need any of 16/48 to get a straight draw, OE or inside, and then either 8/47 or 4/47 to hit the straight...

16/48 * ((8/47 + 4/47)/2) which i make 4.2% (although i'm not completely confident about my maths here).

Anyway, does anyone know which is right?