A fan is needed to ventilate a room of dimensions 2m x 3m x 3m. The air velocity is not to exceed 7 m/s to minimize vibration and noise. The combined efficiency of the fan-motor unit can be taken to be about 50%. If the fan is required to replace the entire volume of air in the room in 15 minutes, determine:A. The input power to the fan-motor unitB. The diameter of the fan casing (shroud)C. The pressure difference across the fan blades