Answer the following questions: (a) (5 marks) Given a fixed amount of workers (N), explain how a higher labour productivity increases the output level. Also explain how, conversely, a higher output level increases labour productivity. (Hint: causality effect.) (b) (10 marks) Empirical evidence suggests that, in the medium run, there is an inverse relation between productivity growth and the unemployment rate. Apply (and illustrate graphically) the theory from chapter 13 in the textbook to explain this phenomenon. (Hint: use the wage setting and price-setting relations.)