It is going to be P times one minus P. Actually, that's the variance. We want to take the square root of that to get the standard deviation. So in this particular scenario, that's going to be the square root of 0.6 times 0.4. Fair enough. This is all review so far. But now let me define, let me define another random variable, X, which is equal to the sum of 10 independent, independent trials, trials, trials of Y. Now, we have seen random variables like this before.