9) For years economists believed that market structure explained the ability of some firms to earn
economic profits. For example, firms in industries with little competition and high barriers to
entry would earn higher profits than firms in competitive industries with low entry barriers.
Which of the following has caused economists to question this explanation and seek other
explanations for why firms are profitable?
A) Studies have shown that, on average, firms in competitive industries earn higher profit rates
than firms in industries with little competition.
B) In recent years new technologies have increased the potential entry of new firms in industries
with high entry barriers.
C) Studies have shown that firms in industries that have little competition and high entry barriers
are not very profitable. Economists conclude from this that some competition is necessary in
order to force firms to lower their costs and develop products that satisfy new consumer
demands.
D) The market structure explanation fails to explain how firms in the same industry can have
very different levels of profit.
10) In recent years online bookseller Amazon.com has lowered its profits by offering some of its
customers free shipping and building more warehouses to hold its inventories. Which of the
following explains Amazon.com’s actions?
A) Amazon.com feared government regulation if its profits were too high.
B) Amazon.com took these actions to deter entry into its market by new online booksellers.
C) Amazon.com took these actions to compete more effectively with existing online booksellers.
D) Amazon.com was forced to take these actions because of the bargaining power of its
suppliers.