A centrifugal compressor has a pressure ratio of 4/1 with an isentropic efficiency of 82% when running at 16000 rpm. It takes in air at 17°C. Guide vanes at inlet give the air a pre-whirl of 20° to the axial direction at all radii and the mean diameter of the eye is 200 mm, the absolute air velocity at inlet is 120 m/s. At exit the blades are radially inclined and the impeller tip diameter is 550 mm. Calculate the slip factor of the compressor.