# Calculus: Other Calculus Problems – #28141

Question: The concentration of drug in a patient’s bloodstream t hours after injection in a person’s bloodstream is given by

$C\left( t \right)=\frac{0.04t}{{{t}^{2}}+1}$

where C(t) is concentration in milligrams per cubic centimeter. At what rate is the concentration changing after one half hour? After two hours? Interpret your answers.