A three-stage centrifugal pump has impellers 40 cm in diameter and 2 cm wide at outlet. The vanes are curved back at the outlet at 45° and reduce the circumferential area by 10 %. The manometric efficiency is 90 % and the overall efficiency 80 %. Determine the head generated by the pump when running at 1000 rpm delivering 50 litres per second, and the shaft power.