Question: In each of the following situations, identify which of the twelve principles is at work.

a. You choose to shop at the local discount store rather than paying a higher price for the same merchandise at the local department store.

b. On your spring break trip, your budget is limited to $35 a day.

c. The student union provides a website on which departing students can sell items such as used books, appliances, and furniture rather than give them away to their roommates as they formerly did.

d. After a hurricane did extensive damage to homes on the island of St. Crispin, homeowners wanted to purchase many more building materials and hire many more workers than were available on the island. As a result, prices for goods and services rose dramatically across the board.

e. You buy a used textbook from your roommate. Your roommate uses the money to buy songs from iTunes.

f. You decide how many cups of coffee to have when studying the night before an exam by considering how much more work you can do by having another cup versus how jittery it will make you feel. g. There is limited lab space available to do the project required in Chemistry 101. The lab supervisor assigns lab time to each student based on when that student is able to come.

h. You realize that you can graduate a semester early by forgoing a semester of study abroad.

i. At the student union, there is a bulletin board on which people advertise used items for sale, such as bicycles. Once you have adjusted for differences in quality, all the bikes sell for about the same price.

j. You are better at performing lab experiments, and your lab partner is better at writing lab reports. So the two of you agree that you will do all the experiments and she will write up all the reports.

k. State governments mandate that it is illegal to drive without passing a driving exam.

l. Your parents' after-tax income has increased because of a tax cut passed by Congress. They therefore increase your allowance, which you spend on a spring break vacation.