i have spent hours on this problem and it is impossible, google hasn't helped

The ends of a water trough have the shape of the region bounded by the graphs of y = x^2 and y = 4 with x and y both measured in feet. To what depth must the trough be filled with water so that the force exerted by the water on either end of the trough is 779.423 lb? (Water has a density of 62.5 lb per cubic foot.)

answer choices are 2.452 feet, 2 feet, 3 feet, 2.351 feet, or 3.528 feet