Marginal—rather than only average or per-unit--costs should guide decisions because marginal costs

A previously well-respected and trusted president of a corporation is accused of fraud. At the same time interest rates unexpectedly fall. Which of the above would tend to make the price of the stock rise?

a. the announcement and the fall in interest rates b. the announcement but not the fall in interest rates c. the fall in interest rates, but not the announcement d. neither the announcement nor the fall in interest rates

In a constant cost industry, the only long-run effect of an increase in demand is ______.

a. an increase in industry output b. an increase of input prices c. a decrease in the number of suppliers d. an increase in the long-run equilibrium price