Chapter 4.6, Problem 14E

The average cost per item, C, in dollars, of manufacturing a quantity q of cell phones is given by

$C=\frac{a}{q}+b\mathrm{where}a,\text{}b\mathrm{are}positivecons\tan ts$

1. (a) Find the rate of change of C as q increases. What are its units?
2. (b) If production increases at a rate of 100 cell phones per week, how fast is the average cost changing? Is the average cost increasing or decreasing?