An axial flow compressor has an overall pressure ratio of 4.0 and mass flow of 160 kg/min. If the polytropic efficiency is 0.88 and stagnation temperature rise per stage must not exceed 25°C calculate the number of stages required and the pressure ratio of the first and last stage. Assume equal temperature rise in all stages. If the absolute velocity approaching the last rotor is 155 m/s at an angle of 20 from the axial direction the work done factor is 0.83 the velocity diagram is symmetrical and the mean diameter of the last stage rotor is 180 mm. Compute the rotational speed and the length of the last stage Ambient conditions are 1.01 bar and 288 K.