A tank has the shape of an inverted circular cone with height 18m and base radius 3m. The tank is filled completely to start, and water is pumped over the upper edge of the tank until the height of the water remaining in the tank is 12m. How much work is required to pump out that amount of water? Use the fact that acceleration due to gravity is 9.8m/sec2 and the density of water is 1000kg/m3. Round your answer to the nearest kilojoule.