A 50 L tank initially contains 2 L of salt water at a concentration of 5 g/L. Salt water at a concentration of 4 g/L is being pumped in at 2 L/min and the mixture is leaving at 1 L/min. Write down BUT DO NOT SOLVE the initial value problem whose solution gives the amount of salt at time 1.

A tank contains 200 gal of liquid. Initially, the tank contains pure water. At time t = 0, brine containing 3 lb/gal of salt begins to pour into the tank at a rate of 2 gal/min, and the well-stirred mixture is allowed to drain away at the same rate. How many minutes must elapse before there are 100 lb of salt in the tank?

A 500 gal capacity tank initially contains 200 gal of water and 5 Ibs of salt per gallon. To reduce the concentration, water at the rate of 3 gal/min enters the tank and the thoroughly mixed solution flows out at the same rate. After 20 min. the process is stopped and brine solution flows into the tank at the same rate of 3 gal/min and at a concentration of 2 Ibs/gal. The mixed solution flows out at the rate of 2 gal/min. Find the amount of salt in the tank 30 min. after resumption of the process. O 699.79 Ib O 717.71 lb O 560.17 Ib O 913.68 Ib

A solution with 35% ammonia is added at a rate of 5 liters per minute to a vat that initially contains 100 liters of pure water. The mixed solution is drained at 3 liters per minute. At what time will the solution contain 10% ammonia?