A trough 7 feet long and 1 foot high is filled with water. The vertical cross-sections of the trough parallel to the ends are shaped like the graph of y = 2 for x = -1 to x = 1. The amount of work required to empty the trough by pumping the water over the top edge is: foot-pounds (Recall that the denisty of water is approximately 62.5 pounds per cubic foot.)