Not mentioned here is the lady’s name, Muriel Bristol.<p>I have also heard that this is a different way with 6 cups. This matters because 6C3 = 6! / (3!(6-3)!) = 20. That 1/20 chance of getting all 3 cups right is said to be the basis for the 5% significance cutoff for p values.<p>Another basis for the 5% cutoff is the (even earlier) Poisson distribution, with zero expected events, 3 observed. In this case, the probability of occurrence by chance is 1/e^3, which is just under 5%. In other words, the 5% p value is analogous to “3 strikes you’re out” because the probability of 3 uncommon events or exceptions is <5%.<p><a href="https://en.m.wikipedia.org/wiki/Muriel_Bristol" rel="nofollow">https://en.m.wikipedia.org/wiki/Muriel_Bristol</a>