1. The problem statement, all variables and given/known data A penny is located at the bottom of a barrel of water 1m deep. There is a 20cm thick layer of oil on top of the water. To an observer at normal incidence, what is the apparent depth of the penny. n for water is 1.33, for oil it is 1.5 2. Relevant equations Snell's law, lots of ray diagrams 3. The attempt at a solution I have already shown that to an observer looking through just the water, the apparent depth is 0.75m. I am just not sure how to generalize this for the other layer. Can someone point me in the right direction?