4. Suppose you are willing to pay $15 for one framed painting in your dorm room and $5 more for a second painting. Your roommate is willing to pay $10 for one painting and has no interest in a second painting.

a. Sketch your individual demand curve for paintings (a step function with maximum quantity of 2). Also sketch your roommate’s demand curve for paintings.

b. Assume you have a divided room such that the paintings are private goods. Sketch the overall demand curve for paintings by both you and your roommate.

c. Instead assume the room is quite open such that each painting is a public good that both you and your roommate can enjoy. Sketch the new social benefit curve (the “market demand”) for paintings.