And one standard deviation above the mean is 10 plus minus 5 is 5. So that's between 5 and 15. So 68.3%, and that's actually always the case, that you have a 68.3% probability of landing within one standard deviation of the mean, assuming you have a normal distribution. So once again, that number comes from, that represents the area under the curve here. This area under the curve. And the way you get it is with the cumulative distribution function. Let me go down here.