Briefly explain the use of graphs as a way to represent economic relationships. What is an inverse relationship? How does it graph? What is a direct relationship? How does it graph? Graph and explain the relationships you would expect to find between
(a) The number of inches of rainfall per month and the sale of umbrellas,
(b) The amount of tuition and the level of enrollment at a university,
(c) The popularity of an entertainer and the price of her concert tickets. In each case cite and explain how variables other than those specifically mentioned might upset the expected relationship. Is your graph in previous part b consistent with the fact that, historically, enrollments and tuition have both increased? If not, explain any difference.