Welcome back. Now let's do a problem that involves almost everything we've learned so far about probability and combinations and conditional probability. So let's say I have a bag again. And in that bag I have 5 fair coins. And I have 10 unfair coins. And a fair coin, of course, there's a 50-50 chance of getting heads or tails. And the unfair coin, let's say that there is a 80% chance of getting a heads for any one of those coins.