Question

If only one quarter of the earth's surface is not covered by bodies of water, and only one half of that exposed land area is inhabitable for humans (because of poles, deserts, etc.), what fraction of the earth's surface can humans live on?

Answer 1

So on the one hand, you could say from these results that 10% of Earth is inhabited by humans. Or you could take a more glass half-empty view and say that 90% of Earth is covered by humans – either populated or connected with an ever-expanding network of roads, train tracks, highways, farms and industrial land.