Question: Opportunity cost is one of the tougher ideas in economics. Let's make it easier by starting with some simple examples. In the following examples, find the opportunity cost: Your answer should be a rate, as in "1.5 widgets per year" or "6 lectures per month." Ignoring Adam Smith's insight from the previous question, assume that these relationships are simple linear ones, so that if you put in twice the time, you get twice the output, and half the time yields half the output.

a. Erin has a choice between two activities: She can repair one transmission per hour or she can repair two fuel injectors per hour. What is the opportunity cost of repairing one transmission?

b. Katie works at a customer service center and every hour she has a choice between two activities: answering 200 telephone calls per hour or responding to 400 emails per hour. What is the opportunity cost of responding to 400 phone calls?

c. Deirdre has a choice between writing one more book this year or five more articles this year. What is the opportunity cost of writing half of a book this year, in terms of articles?