In: Economics
Theory tells us that the real interest rate equals the marginal
product
of capital less the depreciation rate. Theory also tells us that
the marginal
product of capital decreases when the capital-labor ratio
increases. We know
from observation that the capital-labor ratio has been rising
steadily for over a
century, but that the real interest rate and the depreciation rate
have remained
relatively constant. How can all of these statements be correct?
Explain.
Hint: One possible answer uses technological change in an important
way.
Graphing the production function for different technology levels
may be helpful.