a. List and briefly explain the main assumptions we make on consumer preferences. b. For each assumption, provide an example consumer preference that does not satisfy the assumption (you may illustrate your answers by drawing graphs). 2- (10 pts) Consider that there are two goods, good X and good Y. a) Give the definition of "indifference curve". b) Is it possible for two indifference curves to intersect at a certain consumption bundle in (X,Y) plane? If yes, explain and give an example. If not, explain and provide a reason for why it is not possible. 3- (10 pts) Consider that there are two goods, good X and good Y, which are perfect substitutes. The consumer has the utility function given by: U(X,Y)= x + ay The prices of the goods are given by px = 2 and py = 5, respectively. The income of the consumer is given by 1 = 100. a) Choose a value for parameter "a" by yourself. Graphically illustrate the budget line of the consumer and draw some example indifference curves. Then, find the consumption bundle that maximizes the consumer's utility. b) List the possible outcomes for different values of parameter "a".