An aquarium 5 m long, 1 m wide, and 1 m deep is full of water. Find the work needed to pump half of the water out of the aquarium. (Use 9.8 m/s^2 for g and the fact that the density of water is 1,000 kg/m^3.) Show how to approximate the required work (in J) by a Riemann sum. (Let x be the height in meters below the top of the tank. Enter xi* as xi.)