9514 1404 393
Answer:
491,400 ft·lb
Explanation:
The mass of the water is ...
M = Vρ = LWHρ = (25 ft)(15 ft)(7 ft)(62.4 lb/ft³) = 163,800 lb
The average depth is 3 ft, so the work required is equivalent to that required to raise this mass 3 ft.
W = (3 ft)(163,800 lb) = 491,400 ft·lb