This is what this number is right here, this 7%, or actually 0.07 is the area right under there. Now, unfortunately for us in the world, this isn't an easy integral to evaluate analytically, even for those of us who know our calculus. So this tends to be done numerically, and kind of an easy way to do this, well, not an easy way, but a function has been defined called the cumulative distribution function that is a useful tool for figuring out this area. So what the cumulative distribution function is essentially, let me call it, cumulative distribution function, it's a function of x. It gives us the area under the curve, under this curve, so let's say that this is x right here, that's our x. It tells you the area under the curve up to x. Or so another way to think about it, it tells you what is the probability that you land at some value less than your x value, so it's the area from minus infinity to x of our probability density function, dx.