Zachary Du, Chapter 1, Question 6

The example that Charles writes in the book gives us a explicit explanation of the opportunity cost: "My brother began his career as a management consultant with a salary that had at least one more digit than mine has now. On the other hand, he worked long and sometimes inflexible hours. One fall we both excitedly signed up for an evening film class taught by Roger Ebert. My brother proceeded to miss every single class for thirteen weeks". Though Charles' brother could bring higher level of living quality to his family, he lost the opportunity to go to the film class. This ordinary example illuminates the definition of trade-off: every time when people trying to make the best choice, they have to sacrifice the second best option in order to maximize the profit, which is extremely important in the study of economy.