So it's the probability that we get 4 out of 6 heads given a fair coin times the probability of a fair coin over the probability of getting 4 out of 6 heads either way. 4 out of 6 heads. So 4 out of 6 heads given a fair coin, we figured that over here, that's 15 over 64. So this equals 15 over 64. What's the probability that we picked a fair coin? Well, there's 15 coins, and 5 of them are fair, so it's 5 out of 15, so it's 1 third. And what's the probability that, in general, we picked 4 out of 6 heads?