1. The problem statement, all variables and given/known data A 200 gallon tank initially contains 100 gallons of water with 20 pounds of salt. A salt solution with 1/4 pound of salt per gallon is added to the tank at 4 gal/min, and the resulting mixture is drained out at 2 gal/min. Find the quantity of salt in the tank as it's about to overflow. 2. Relevant equations None. 3. The attempt at a solution (1/4)lbs/gal*(4)gal/min=1lbs/min (Q)lbs/100 gal*(2)gal/min=Qlbs/50 min dQ/dt=1-Q/50=(50-Q)/50 50/(50-Q)dQ=dt -50ln abs(50-Q)=t+C ln abs(50-Q)= -t/50+C 50-Q=Ce^(-t/50) Q=50-Ce^(-t/50) Q(0)=0 C=50 Q(t)=50(1-e^(-t/50)) Q(50)=31.606 But the answer is Q(50)=47.5 Where did I make a mistake?