 To make sure that we understand scaling, we're going to have a look at three worked examples now. I'll tell you what they are and then I want you to have a go at them before you look at the next video. In the next video I'll walk you through how to do it and if you haven't had a go then it's not going to be as useful. Question one. Question two. And question three. So when you're typing on a computer and you select a point size, it might be 32 point or something, the point is just a unit of length. It's just how big those letters are supposed and one point is roughly a third of a millimeter. Obviously when you build a scale model of house you don't need as much wood and paint as you need to build the full size house so you can work out that. So obviously the population density in the country is lower than the population density in the city. In fact by a long way this might not even be an accurate figure but I just plucked it out of nowhere and we can use it for our calculation. And I want you to figure out how the population density affects how the distance between people changes.