44. Drug Diffusion in the Bloodstream After a drug is taken orally, the amount of the drug in the bloodstream after t hours is f(t) units. Figure 27 shows partial graphs of f'(t) and f"(t). 3 1 Y -3 Figure 27 y = f'(t) 3 y = f(t) 5 7 t (a) Is the amount of the drug in the bloodstream increasing or decreasing at = 5 hours? (b) Is the graph of f(t) concave up or concave down at 1 = 5 hours? (c) When is the level of the drug in the bloodstream decreas- ing the fastest? (d) At what time is the greatest level of drug in the blood- stream reached? (e) When is the level of the drug in the bloodstream decreas- ing at the rate of 3 units per hour?