The quantity, Q mg, of nicotine in the body t minutes after a cigarette is smoked is given by Q = f(t).
(a) Interpret the statements f(20) = 0.36 and f'(20) = −0.002 in terms of nicotine. What are the units of the numbers 20, 0.36, and −0.002?
(b) Use the information given in part (a) to estimate f(21) and f(30). Justify your answers.