Economists sometimes make each of the following assumptions when they construct models. Discuss some situations in which each of these assumptions might be a useful simplification in order to think about some aspect of the real world.
a. Earth is flat.
b. There are no differences between men and women.
c. There is no tomorrow.
d. There are only two periods: this year and next year.
e. A country produces only two types of goods.
f. People are wholly selfish.