4. Suppose the economy is in a long-run equilibrium.

a. Draw the economy's short-run and long-run Phillips curves.

b. Suppose a wave of business pessimism reduces aggregate demand. Show the effect of this shock on your diagram from part (a). If the Bank of Canada undertakes expansionary monetary policy, can it return the economy to its original inflation rate and original unemployment rate?

c. Now suppose the economy is back in long-run equilibrium, and then the price of imported oil rises. Show the effect of this shock with a new diagram like that in part (a). If the Bank of Canada undertakes expansionary monetary policy, can it return the economy to its original inflation rate and original unemployment rate?

If the Bank of Canada undertakes contractionary monetary policy, can it return the economy to its original inflation rate and original unemployment rate? Explain why this situation differs from that in part (b).