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. And there's actually an Excel, when you actually use the Excel normal distribution function, you say norm distribution, you have to give it your x value, you give it the mean, you give it the standard deviation, and then you say whether you want the cumulative distribution, in which case you say true, or you want just this normal distribution, which you say false. So if you wanted to graph this right here, you would say false, in caps. If you wanted to graph the cumulative distribution function, which I do down here, let me move this down a little bit, let me get out of the pen tool, so the cumulative distribution function is right over here, then you say true when you make that Excel call. So this is a cumulative distribution function for the same, for this, this is a normal distribution, here's a cumulative distribution. And just so you get the intuition, if you want to know what is the probability that I get a value less than 20, so I can get any value less than 20 given this distribution, the cumulative distribution right here, let me make it so you can see the, if you go to 20, you just go right to that point there and you say wow, the probability of getting 20 or less, it's pretty high, it's approaching 100%, that makes sense because most of the area under this curve is less than 20. Or if you said what's the probability of getting less than minus 5, well minus 5 was the mean, so half of your result should be above that and half should be below.