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.
The Attempt at a Solution
(Q)lbs/100 gal*(2)gal/min=Qlbs/50 min
ln abs(50-Q)= -t/50+C
But the answer is Q(50)=47.5
Where did I make a mistake?