Water is pumped from a lake to a storage tank 15 m above at a rate of 60 L/s while consuming 17.5 kW of electric power. Disregarding any frictional losses in the pipes and any changes in kinetic energy, determine the overall efficiency of the pump-motor unit' Disregarding any frictional losses in the pipes and any changes in kinetic energy, determine

a) the overall efficiency of the pump motor unit and
b) the pressure difference between the inlet and the exit of the pump.