Consider a large classroom on a hot summer day with 150 students, each dissapating 60W of sensible heat. All the lights, with 6.0kW of rated power, are kept on. The room has no external walls, and thus heat gain through the walls and the roof are negligible. Chilled air is available at 15 degrees C, and the temperature of the return air is not to exceed 25 degrees C. Determine the flow rate of the air, in kg/s that need to be supplied to the room to keep the average temperature of the room constant.