When you take a single dose of a drug (such as aspirin or paracetamol), the concentration of the drug in your blood decays along an exponential curve, at least approximately. Thus, if C(t) is the blood concentration of the drug as a function of time, we know that a reasonable model is C( cise 4.19.
t) = C0e −r t , for some constants C0 and r.

a. If C has units of mM, and t has units of s, what are the units of C0 and r?

b. What are the scientific meanings of the constants C0 and r?

c. Use the limit definition of the derivative to calculate C 0 (t).

d. What is limt→∞ C(t)?

e. What is limt→∞ C 0 (t)?

f. Do the last two results make scientific sense?