If time, t, is in hours and concentration, C, is in ng/ml, the drug concentration curve for a drug is given by 

C = 12.4te^−0.2t.

(a) Graph this curve.
(b) How many hours does it take for the drug to reach its peak concentration? What is the concentration at that time?
(c) If the minimum effective concentration is 10 ng/ml, during what time period is the drug effective?

(d) Complications can arise whenever the level of the drug is above 4 ng/ml. How long must a patient wait before being safe from complications?