If the rotative speed is 3000 rpm and manometric efficiency 0·8 then what is the net head developed?

Question

A centrifugal pump with radial vane tips at the outlet has an impeller of 100 mm outer diameter. If the rotative speed is 3000 rpm and manometric efficiency 0·8 then what is the net head developed?

                                             

(a) 10 m                       (b) 20 m

(c) 30 m                       (d) 40 m