1. (10) An automobile mechanic is working on a poorly running engine in their shop. It is the dead of winter and the exhaust is connected to the outside via a rubber tube. The engine is idling and producing exhaust gases at a rate of 10 ft/min (at 0.9 atm pressure and 22 C). The carbon monoxide content of the exhaust is 2% by volume. The telephone rings at exactly the time that the exhaust tubing becomes detached from the automobile tailpipe. The mechanic hurries to the adjoining room and answers the phone - and engages in a lengthy conversation. The garage is 20' x 20' x 10' and is equipped with a ventilation system that exhausts 30 ft3/min of air from the garage with input air drawn through a louver. A CO level of 500 ppm, is associated with highly acute detrimental health effects. How long (in minutes) after the hose is detached it will take for the CO concentration to reach this dangerous level? (10.4 min)