A large tank is filled to capacity with 400 gallons of pure water. Brine containing 5 pounds of salt per gallon is pumped into the tank at a rate of 4 gal/min. The well-mixed solution is pumped out at a rate of 8 gals/min. Find the number A(t) of pounds of salt in the tank at time t. A(t)

If  is the amount of salt in the tank at time , then the rate at which the amount of salt in the tank changes is given by

Let's drop the units for now. We have

We're given that the water is pure at the start, so , giving

So the amount of salt in the tank (in lbs) at time  is

Step-by-step explanation:

34

step-by-step explanation: