Final answer:
The agreement by OPEC to increase oil output resulting in lower oil prices typically leads to a rightward shift in the short-run aggregate supply curve, reflecting temporary lower production costs, but does not affect the long-run aggregate supply curve unless the change is permanent.
Step-by-step explanation:
When the Organization of Petroleum Exporting Countries (OPEC) agrees to increase oil output leading to lower oil prices for six months, there is typically a shift in the short-run aggregate supply curve (SRAS), but not necessarily in the long-run aggregate supply curve (LRAS). The reason for this is that the change is temporary (lasting only six months) and does not reflect a permanent increase in the economy's productive capacity. Lower oil prices reduce the cost of production for many goods and services, leading to an outward shift in the SRAS to the right, indicating that at each price level, a greater quantity of goods and services can be supplied.
In the case of a long-term increase in oil output, however, which might suggest a more permanent change in production costs, the long-run aggregate supply (LRAS) could also shift to the right. In the context given by Figure 5.11, a leftward shift of the supply curve demonstrates what occurs when OPEC restricts oil output—it increases the price of oil and reduces the quantity demanded. An increase in oil output would have the opposite effect, providing temporary relief to cost pressures and improving short-term economic output, without necessarily affecting the economy's long-term potential (LRAS).