Absorption of Drugs The concentration of a drug in an organ at any time t (in seconds) is given by S0.3t - 18(1 - e-t/60) 18e-t/60 - 12e-(t - 20)/60 if t > 20 if 0 sts 20 C(t) where C(t) is measured in milligrams per cubic centimeter (mg/cm3). (a) What is the initial concentration of the drug in the organ? mg/cm3 (b) What is the concentration of the drug in the organ after 13 sec? (Round your answer to three decimal places.) 0.394 mg/cm3 (c) What is the concentration of the drug in the organ after 38 sec? (Round your answer to three decimal places.) mg/cm3