A golden-colored cube is handed to you. The person wants you to
buy it for $100, saying that it is a gold nugget. You pull out your
trusty geology field guide for reference and find that gold has a
density of 19.3 g/cm³. You measure the cube and find that it is 2
cm on each side and has a mass of 40 g. Should you buy the cube?
(P.S. the current price of gold is about $65 a gram)