The Hardboard Construction Company hired Bob at $10 an hour, but its output of doll houses only increased by three units a day. Two weeks later, the company purchased an $8 hammer for Bob and output increased by twelve units. Since the hammer increased

the marginal product more than Bob did, and at less cost, Hardboard fired Bob. Is this consistent with the theory of marginal productivity? Why or why not?

This example illustrates a minor flaw with the marginal productivity theory. Sometimes it is difficult to distinguish the output of an additional worker from that of the additional tool used by the worker. In this case, Bob was less productive without the hammer, but how productive will the hammer be without Bob?