A transmission shaft, rotating at 500 r.p.m., drives a milling machine which requires 3.75 kW at 750 r.p.m. A 300 mm diameter cast iron pulley is mounted on the transmission shaft. A preliminary design proposes using a belt 4.75 mm thick, which has a density of 970 kg/m3. The allowable stress is 2 MPa. Two pulleys rotate in opposite directions and the centre distance of the shafts is 750 mm. The coefficient of friction is 0.3 for both the pulleys. Determine the width of the belt.