Mark consumes only cookies and books. At his current consumption bundle, his marginal utility frombooks is 10 and from cookies is 5. Each book costs $10, and each cookie costs $2. Is he maximizing his utility? Explain. If he is not, how can he increase his utility while keeping his total expenditure constant?

2.5 Ms. Caffeine enjoys coffee (C) and tea (T) accord- ing to the function U(C,T) = 3C+4T. a. What does her utility function say about her MRS of coffee for tea? What do her indiffer- ence curves look like? b. If coffee and tea cost $3 each and Ms. Caffeine has $12 to spend on these products, how much coffee and tea should she buy to maximize her utility? c. Draw the graph of her indifference curve map and her budget constraint, and show that the utility-maximizing point occurs only on the T-axis where no coffee is bought. d. Would this person buy any coffee if she had more money to spend? e. How would her consumption change if the price of coffee fell to $2?

Pam has a monthly budget of £120 to be spent on T-shirts and trainers. She could afford to buy two T-shirts and two pairs of trainers. She could also buy eight T-shirts. In each case, she would be spending her entire monthly allowance. Calculate the price of a T-shirt and the price of a pair of trainers. Write down Pam’s budget equation and draw the corresponding budget line. Mark the two consumption bundles mentioned above. In your graph, clearly label the axes, the budget line, and calculate the coordinates of the points of intersection of the budget line with each axis. Interpret each of those points. Discuss how Pam’s budget set would change if the price of a T-shirt doubles. Show the relevant changes graphically. How should Pam’s income change so that she could still afford to buy two T-shirts and two pairs of trainers? Discuss how Pam’s budget constraint would change if the government imposed a tax of £3 per each pair of trainers.

Luke has a monthly income of $80. He spends this money making telephone calls from home (measured in minutes of calls) and on other goods. His mobile phone company offers him two plans: Plan A: Pay no monthly fee and make calls for $0.50 per minute. Plan B: Pay a $30 monthly fee and make calls for $0.1 per minute.  Graph Luke’s budget constraint under each of the two plans.