Aswimming pool has the shape of a box with a base that measures 21 m by 14 m and a depth of 3.1 m. how much work is required to pump the water out of the pool when it is? full? use 1000 kg divided by m cubed for the density of water and 9.8 m divided by s squared for the acceleration due to gravity.

The work needed to pump the water would have the units of Joules or Pa*m^3. From here, this would be a hint that you only multiply the hyraulic pressure and its volume.

Hydraulic pressure = density*gravity*height = 1000*9.8*3.1 = 30,411 Pa
Volume = 21*14*3.1 = 911.4 m^3
Work = 30,411*911.4 = 27,716,585.4 J = 27.72 MJ