Chapter 6.5, Problem 7TE

Absorption OF DRUGS The concentration of a drug in an organ t seconds after it is administered is given by

$\text{A}(\text{t})=\{\begin{array}{ll}0.3t-18(1-{\text{e}}^{-\text{t}/60})\hfill & if\text{ 0}\le \text{t}\text{ < 20}\hfill \\ 18{\text{e}}^{-\text{t}/60}-12{\text{e}}^{-(\text{t}-20)/60}\hfill & if\text{t}>20\hfill \end{array}$

where C(t) is measured in grams per cubic centimeter (g/cm⁵). Find the average concentration of the drug in the | organ over the first 30 sec after it is administered.