As Shown in the Figure, a Large Open Tank Contains $\text { (density } 450 \mathrm {~kg} / \mathrm { m } ^ { 3 } \text { ) }$

Short Answer

As shown in the figure, a large open tank contains a layer of oil $\text { (density } 450 \mathrm {~kg} / \mathrm { m } ^ { 3 } \text { ) }$
floating on top of a layer of water $\text { (density } \left. 1000 \mathrm {~kg} / \mathrm { m } ^ { 3 } \right)$
that is 3.0 m thick, as shown in the sketch. What must be the thickness of the oil layer if the gauge pressure at the bottom of the tank is to be $8.5 \times 10 ^ { 4 } \mathrm {~Pa} ?$