The standard deviation we're assuming with our null hypothesis divided by the square root of the number of samples we have. And in this case, we have 150 samples. It's going to be 150 samples, and we can calculate this. This value on top, we just figured out, is the square root of 0.21. So this is the square root of 0.21 over the square root of 150, and I can get the calculator out to calculate this, so I'll just do it the way I wrote it. Square root of 0.21, and I'm going to divide that, so whatever answer is, I'm going to divide that by the square root of 150. So it's 0.037.