The variance is probability of left times probability of right times total number of moves. And then the normal probability, once again, I just use the normal probability, I just use the, so I approximate it the same way. So for example, in this situation right here, and Excel has a normal distribution function, but I actually typed in the formula because I wanted to kind of see what was under the covers for that function that Excel actually has. So I actually say, what's the probability of 45 left moves? So I say the probability of 45 left moves is equal to 1 over the standard deviation. So in this situation, the standard deviation is the square root of 25, so it's 5 times 2 pi times e to the minus 1 half times 45 minus the mean, minus 50, over the standard deviation, which we figured out was 5, squared. So that tells me the value of what the normal distribution tells me for this situation with this standard deviation and this mean.