Question: 1. Suppose C(r) is the total cost of paying off a car loan borrowed at an annual interest rate of r%. What are the units of C'(r)? What is the practical meaning of C'(r)? What is its sign?
2. Let f(x) be the elevation in feet of the Mississippi River x miles from its source. What are the units of f' (x)? What can you say about the sign of f'(x)?