A water tank has the shape obtained by revolving the parabola y = 0.50x2 around the y-axis. Its bottom has a circular hole of diameter 1 in. which was opened when the water depth was 9 ft. a. Set up a differential equation (DE) for the water level in the tank as a function of time. b. Solve the DE to find an expression for the water level as a function of time. c. When will the tank be empty ? Your