A centrifugal pump rotating at 1500 r.p.m. delivers 0.2 m3/s at a head of 15 m. Calculate the specific speed of the pump and the power input. Assume overall efficiency of the pump as 0.68. If this pump were to operate at 900 r.p.m. what would be the head, discharge and power required for homologous conditions? Assume overall efficiency unchanged at new r.p.m.