Use the following information to answer Exercises. A certain drug is given to a patient every 12 hours. The steady state concentration function is given by C_ss(t) = 1.99De ^-0.14t - 1.62De^-2.08t mcg/mL, where D is the size of the dose in milligrams.
1. If a 500-mg dose is given every 12 hours, find the maximum and minimum steady-state concentrations.

2. If the dose is increased to 1500 mg every 12 hours, find the maximum and minimum steady-state concentrations.
3. What dose should be given every 12 hours to maintain a steady-state concentration between 80 and 400 mcg/mL?