A rectangular tank that is 4 feet long, 6 feet wide and 12 feet deep is filled with a heavy liquid that weighs 80 pounds per cubic foot. In each part below, assume that the tank is initially full. Your answers must include the correct units. (You may enter lbf or Ib*ft for ftIb.) (a) How much work is done pumping all of the liquid out over the top of the tank? 138240 lbf (b) How much work is done pumping all of the liquid out of a spout 3 feet above the top of the tank? (0) How much work is done pumping two-thirds of the liquid out over the top of the tank? 61440 lbf (d) How much work is done pumping two-thirds of the liquid out of a spout 3 feet above the top of the tank