A centrifugal pump running at 200 rpm and at its maximum efficiency is delivering a head of 30 m at a flow rate of 60 l/min. If the speed of the pump is increased to 400 rpm, then head H in meters and flow rate Q in l/min at maximum efficiency is
1
H = 60, Q = 120
2
H = 120, Q = 240
3
H = 120, Q = 120
4
H = 60, Q = 240