An open top tank contains a layer of SAE 30 oil 0.5 m thick, a layer of water 0.7 m thick, and a layer of mercury 0.3 m thick. Calculate the pressure, and the piezometric head at the free surface, at both interfaces, and at the tank bottom. Take the elevation datum at the bottom of the tank. Graph the pressure and piezometric head in the tank as functions of elevation.