Work Energy And Power

A pump on the ground floor of a building can pump up water to fill a tank of volume $36 \mathrm{~m}^3$ in 30 min . If the tank is 50 m above the ground, and the electric power consumed by the pump is 40 k W , the efficiency of the pump is

(use $g=10 \mathrm{~m} / \mathrm{s}^2$ and density of water $=1000 \mathrm{~kg} / \mathrm{m}^3$ )