In the Figure, an Open Tank Contains a Layer of Oil

Short Answer

In the figure, an open tank contains a layer of oil floating on top of a layer of water (of density 1000 kg/m³) that is 3.0 m thick, as shown. What must be the thickness of the oil layer if the gauge pressure at the bottom of the tank is to be 5.0 x 10⁴ Pa? The density of the oil is 510 kg/m³.