You've two measuring cups: one holds exactly 5 ounces of water and the other holds exactly 3 ounces of water. There're no markings on the cups and you are not able to mark the cups at all. You are given access to a fountain of limitless water. Is it possible to measure and place exactly 4 ounces of water into the big cup? If so, carefully explain your method; if not, carefully explain why not.