This is the s right here. This is the s right over here. This 0.50 divided by 10, which is equal to 0.05. So our best estimate of this standard deviation is 0.05, or you could even view it as 5%. Now, what I want to do is come up with an interval around this sample mean where I'm reasonably confident, using all of my estimates and all of that, where I'm reasonably confident that there's a 95% chance that the true mean is within two standard deviations. Or let me put it this way. There's a 95% chance that the true mean is in that interval.