https://www.npr.org/sections/money/2014/10/03/353300404/episode-573-why-textbook-prices-keep-climbing

1. Economist James Koch, when talking about the textbook he assigned in his classes, stated he knew it was well written, it has good problems, but he didn't know what?
2. What is the principal - agent problem?
3. According to Greg Mankiw, the economist who wrote the expensive textbook, what other markets do consumers rely on other individuals to make informed decisions?
4. Why do publishers earn a lower profit margin on high school textbooks than with college textbooks?
5. How is the used textbook market helping to drive up the price of textbooks?