Situation 2 A doctor administers medicine to a patient. The level of drug in the bloodstream measured in milligrams after t hours is given by the function: M (t) = 500 (14) 15 (a) What was the amount of medicine administered by the doctor at the beginning? (b) Determine whether the function represents growth or decay. How do you know? (c) Find the effective relative rate of change. Express the answer as a fraction. (d) How much medicine is in the bloodstream after 4 hours? (e) If the patient needs at least 150 mg in the bloodstream, after how many hours should the patient get another dose? Note on Rates In an exponential function y = C . a*, the base a is called the growth or decay factor. The effective relative rate of change of an exponential function y = C . a* is given by: re = la - 11. The relative rate of change of an exponential function y = C . a* is given by the formula: r = In a