Water is leaking out of an inverted conical tank at a rate of 10,000 at the same time that water is being pumped into the tank at a constant rate. The tank has a height 6m and the diameter at the top is 4m. If the water level is rising at a rate of 20 cm/min when the height of the water is 2m, find the rate at which water is being pumped into the tank.