But when people just say mean, they're usually talking about the arithmetic mean. So how would you go about finding the mean height of men in the United States? Well, the obvious one is, is well, you go and ask every, or measure every man in the United States, take their height, add them all together, and then divide by the number of men there are in the United States. But the question you need to ask yourself is whether that is practical. Because you have on the order, let's see, there's about 300 million people in the United States, roughly half of them will be men, or at least they'll be male. And so you will have 150 million, roughly 150 million men in the United States. So if you wanted the true mean height of all of the men in the United States, you would have to somehow survey, or not even, you would have to be able to go and measure all 150 million men.