You are in an old spy movie and have been locked in a small room (V=1000 ft3 ). You suddenly realize that a poison gas has just started entering the room through a ventilation duct. Recognizing the type of poison from its smell, you know that if the gas reaches a concentration of 100 mg/m3 , you will die instantly, but that you are safe as long as the concentration is less than 100 mg/m3 . If the ventilation air flow rate in the room is 100 ft3 /min and the incoming gas concentration is 200 mg/m3 , how long do you have to escape? You may assume that the air in the small room is well-mixed.