You are in an old spy movie, and have been locked into a small room (volume 1000 ft). 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/m, you will die instantly, but that you are safe as long as the concentration is less than 100 mg/m. If the ventilation air flow rate in the room is 100 ft/min and the incoming gas concentration is 200 mg/m, how long do you have to escape?