The small two-story office building shown in Fig.P4.10 has 36,000 ft3 of occupied space. Due to cracksaound windows and outside doors, air leaks in on the windward sideof teh building and leaks out on the leeward side of the building.Outside air also enters the building when outer doors are opened.On a particular day, tests were conducted. The outdoor temperaturewas measured to be 15 degrees F. The inside temperature wascontrolled at 70 degrees F. Keeping the doors closed, theinfiltration rate through the cracks was determined to be 75ft3/min. The infiltration rate associated with dooropenings, averaged over the work day, was 50 ft3/min.The pressure difference was negligible between the inside andoutside of building. (a) Assuming ideal gas behavior, determine atsteady state the volumetric flow rate of air exiting the building,in ft3/min. (b) When expressed in terms of teh volume ofthe occupied space, determine the number of building air changesper hour.