What is the probability that the woman is taller than the man? Well we can rewrite that question as saying, what is the probability that the random variable D is, what conditions would it be? Pause the video and think about it. Well the situations where the woman is taller than the man, if the woman is taller than the man, then this is going to be a negative value. Then D is going to be less than zero. So what we really want to do is figure out the probability that D is less than zero. And so what we want to do, if we say zero is right over, if we said that zero is right over here on our distribution, so that is D is equal to zero, we want to figure out, well what is the area under the curve less than that?