"A rectangular building is being designed to minimize heat loss. The east and west walls lose heat at a rate of 10 units/m^2 per day , the north and south walls at a rate of 8 units/m^2 per day , the floor at a rate of 1 unit/m^2 per day , and the roof at a rate of 5 units/m^ per day. Each wall must be at least 30 m long , the height must be at least 4m , and the volume must be exactyl 4000m^3." Does this mean that both the length and the width are 30 meters meanwhile the height is 4m?