29

The concentration of a drug in the body decreases exponentially after a dosage is given. In one clinical study, adult subjects averaged 13 micrograms/milliliter (mcglmL) of the drug in their blood plasma 1 hr after a 1000-mg dosage and 4 micrograrslmilliliter 5 hr after dosage. all Find the value k, and write an equation for an exponential function that can be used to predict the concentration of the drug, in microgramslmil-liliter, t hours (after a 1000-rng.dosage. b) Estimate the concentration of the drug 3 hr after a moo-mg dosage. c) To relieve a fever, the concentration of the drug should go no lower than 2 moglrnL. After how many hours will a 1000-mg dosage drop to that level? a) k = '3 (Round to three decimal places as needed.) Choose the correct equation below. 0 A. P(t)=13e \"0-2951 0 l3. \"0:19.500 3 e0.885t' 0 '2 Pttl= 1?.5e \"0385' r O D. p(t)=19.5008'-0L295t O 5- P(t)=15.500e '0-2951 O F. pm=13 3 1.1751 0 6- P(t)=17.5e '0-295t ' - O H. pmgne 0.415t b) The concentration of the drug after_3 hr will be about I] mcg/mL. ' (Round to one decimal place as needed.) c) After about [3 hr the concentration of the drug will have dropped to 2 mcglmL. (Round to the nearest integer as needed.)