The concentration of a drug in the body decreases exponentialy after a dosage is given In ene clinical atudy. adull subjects averaged 13 microgramsimiliner (micgint.) of the drug in their blood plasma 1 he after a 1000 -itg dosage and 3 microgramsimilliner 7 hir after dosage a) Find the value k, and wihe an equation for an expenential function that can be used to predict the concentration of the drug. in microgramsienimitec, theurs afler a 1000-mng dosage b) Estimate the concentration of the drug 3 hr atter a 1000 -ng dosage c) To relieve a fever, the concentration of the drug should go no lower than 3 mogind. Atter how many hours will a 1000 -mg dosage diop to that lovel