Getting exactly this, this is exactly 1 out of a possible of 16 events. Now with that out of the way, let's think about how many possibilities, how many of those 16 possibilities involve getting exactly 1 heads. Well, we could list them. You could get your heads. So this is equal to the probability of getting the heads in the first flip plus the probability of getting the heads in the second flip plus the probability of getting the heads in the third flip. Remember, exactly 1 heads. We're not saying at least 1, exactly 1 heads.