A vertical shaft Francis turbine rotates at 300 rpm. The available head at the inlet to the turbine is 200 m. The tip speed of the rotor is 40 m/s. Water leaves the runner of the turbine without whirl. Velocity at the exit of the draft tube is 3.5 m/s. The head losses in different components of the turbine are :

(i) stator and guide vanes: 5.0 m,

(ii) rotor: 10 m, and

(iii) draft tube: 2 m.

Flow rate through the turbine is 20 m³ /s. Take 𝒈 = 9.8 m/s² . The hydraulic efficiency of the turbine is ______________ % (round off to one decimal place).