Many hydroelectric systems utilise a backup reservoir in times of high demand. Filling a back up reservior requires more energy than can be obtained...

Many hydroelectric systems utilise a backup reservoir in times of high demand. Filling a back up reservior requires more energy than can be obtained from its use. Calculate the power required (in MW) to pump water into a backup reservoir 25 metres above the water level, if the pumps operate at a flow rate of 15,000 litres per second and the pipe friction reduces the efficiency of pumping by 18%. (g=9.81 m.s-2 and the density of water is 1000 kg.m^-3)