In the last video, we figured out the probability of getting exactly 3 heads when we have 5 flips of a fair coin. What I want to do in this video is think about it in a slightly more general way. We're still going to assume we have a fair coin, although we'll shortly see we don't have to make that assumption. What I want to do is figure out the probability of getting k heads in n flips of the fair coin. The first thing to think about is how many possibilities there are. There's going to be n flips, so literally there's first flip, second flip, third flip, all the way to the nth flip. This is a fair coin.