And similarly, if I were to ask you the difference, if I were to say, well what's the, how many more cats in a given day would I expect to see than dogs, so the expected value of Y minus X? What would that be? Well, intuitively, you might say, well, hey, if we can add random, if the expected value of the sum is the sum of the expected values, then the expected value or the mean of the difference will be the differences of the means, and that is absolutely true. So this is the same thing as the mean of Y minus X, which is equal to the mean of Y, is going to be equal to the mean of Y minus the mean of X minus the mean of X, and in this particular case, it would be equal to four minus three, minus three is equal to one. So another way of thinking about this intuitively is I would expect to see on a given day one more cat than dogs. Now, the example that I've just used, this is discrete random variables, on a given day, I wouldn't see 2.2 dogs or pi dogs. The expected value itself does not have to be a whole number because you could, of course, average it over many days, but this same idea that the mean of a sum is the same thing as the sum of means and that the mean of a difference of random variables is the same as the difference of the means.