A pump runs under a head of 40.8 m with discharge 30 L/s; the head loss is 4 m. The motor (efficiency 90 %) draws 25 A from a 3-phase 400 V line at PF 1. Determine the pump efficiency. Take 40.8 m as the static head, so the pump must also overcome the 4 m loss. (Take g = 9.81 m/s²; answer in %.)