Suppose that in the economy of Idaho, Amy earns an income of $50,000 a year and pays $10,000 in income taxes; Bailey earns an income of $25,000 a year and pays $8,000 in income taxes. Based on this information, we could say that Idaho's tax system is

The De Beers diamond mining and marketing company of South Africa became one of the most profitable and longest-lived monopolies in history. Which of the following has always threatened De Beers' control of the diamond market?

A) At different times in the past some countries have banned the importation of diamonds from South Africa for political reasons. B) Competition from imitation diamonds. Technology has made it possible to make fake diamonds look exactly like real diamonds. C) Competition from other gemstones, including rubies and emeralds, that have become more popular over time. D) Since few diamonds are ever destroyed, De Beers has constantly faced possible competition from other firms reselling diamonds.

We can measure the profits earned by a firm in a competitive industry as

a. (P - ATC) × Q. b. (P - MC) × Q. c. MR × MC. d. (MC - ATC) × Q.