A Kaplan turbine develops 24 647.6 kW at an average head of 39 m. Assuming a speed ratio of 2, flow ratio of 0.6, diameter of the boss = 0.35 × diameter of the runner and an overall efficiency of 90 %, calculate (a) the runner diameter (m), (b) the speed (rpm) and (c) the specific speed (N in rpm, P in kW, H in m).