3. A common assumption in modeling drug assimilation is that the blood volume in a person is a single compartment that behaves like a stirred tank. Suppose that the blood volume is a four- Iiter tank that initially has a zero concentration of a particular drug. At time t=0, an intravenous line is inserted into a vein (into the tank) that carries a drug solution with a concentration of 500 mg/L. The inflow rate is 0.05 L/min. Assume the drug is quickly mixed thoroughly in the blood and that the volume of blood remains constant (so you can assume the outow rate is 0.06 L/min.) a. Write an initial value problem that models the mass of the drug in the blood for t20. b. Solve the initial value problem to determine the mass of the drug at time t. c. Determine when the mass of the drug reaches 1800 mg