And then we're going to have plus, one minus 2.1 is negative 1.1, and then we're going to square that. So that's just going to be the same thing as 1.1 squared, which is 1.21, but I'll just write it out. 1.1 squared times 0.15, and then this is going to be two minus 2.1 is negative 0.1 when you square it is going to be equal to, so plus 0.01. If you have negative 0.1 times negative 0.1, that's 0.01 times 0.4 times 0.4, and then plus, this is going to be 0.9 squared, so that is 0.81 times 0.25, and then we're almost there. This is going to be plus 1.9 squared, 1.9 squared times 0.1, and we get 1.19. So this is all going to be equal to 1.19, and if we want to get the standard deviation for this random variable, and we would denote that with the Greek letter sigma, the standard deviation for the random variable X is going to be equal to the square root of the variance. The square root of 1.19, which is equal to, let's just get the calculator back here.