5lbs Co2 tank???

I found a 5lbs co2 tank with regulator for $100 on craigslist. how long would a 5lbs tank last in a 10x12 room? Im guessing a week?

ok from the co2 calculator it lasts not even 2days

Yea RU thanks for your help but whatever just picked up cap regulator and 5 gallon tank for $115 then picked up a 20gal tank for another $60. Pissed cause there aren't any co2 refill stations open on the weekend so gotta wait till Monday.....