Thats .4%, .4 implies they have a 40% chance of winning .4% is a 1/250 shot
Its simple really. To find the probability of an even occurring twice in a row you multiply the probability of that event occurring by itself (assuming the odds are separated from each other). So if you want to find the odds of flipping heads twice in a row you multiply .5*.5 = .25 or 25%
Now if you want to find the probability of an event occurring 6 times in a row, well you just multiply the probability by itself 6 times.
so if you say the odds of a top female pro beating a top male pro are .2 (20%) then the odds of that female pro winning the Open are .2*.2*.2*.2*.2*.2=.000064 or 0.0064% chance of winning the tournament. Now because there were 3 women in the single elimination bracket, that multiplies the odds of a woman winning by 3 (actually slightly more than 3 if they can draw each other) so the odds of a woman winning the predator open from the knock out stages is roughly .02% if you assume they have a 20% chance against any top tier male in any given set (and that all the men in the single elimination bracket were top tier players).
