1. The problem statement, all variables and given/known data A large tank initially hold 40 gallons of water. Pure alcohol enters at a rate of 2 Gal/min is well stirred and the mixture leaves at 1gal/min. What will be the concentration when of alcohol when the tank has 80 gallons of fluid in it. 2. Relevant equations q= amount of alcohol i have dq/dt=rate in -rate out rate in=2gal/min of OH it will take 40 mins to fill to 80 gal and the thing im wandering about is the rate out. i currently have rate out=q/(40+2t), but im thinking maybee its q/(40+t) as for the rest i think im fine its just this outflow rate im not sure on.