Plus the other 108 times, we got a 0, so we were 0 minus 0.568 away from the sample mean. Then we are going to divide that by the total number of samples minus 1. That minus 1 is our adjuster so that we don't underestimate. 250 minus 1, let's get our calculator out again. We have 142 times 1 minus 0.568 squared plus 108 times 0 minus 0.568 squared, and then all of that divided by 250 minus 1 is 249. Our sample variance is 0.246. If you were to take the square root of that, our actual sample standard deviation is 0.496.