An underground tank is a hemisphere with radius 4 feet (i.e. it
is half a sphere, and so horizontal cross-sections are circles of
varying radius). It is filled to the top with oil weighing 45 lb
per cubic foot. The top of the tank is at ground level, and the oil
in the tank is pumped to a height of 10 feet above ground level.
How much work is done? Set up the integral, but then just use your
calculator...