If an industry has 25 firms that collectively have $150 million in total sales and the top four firms in this industry account for $90 million in sales, what is the concentration ratio of the top four firms in this industry?

Fluctuations in the demand for reserves cause the Fed to lose control over a monetary aggregate if the Fed targets

A) a monetary aggregate. B) the monetary base. C) an interest rate. D) nominal GDP.

An example of moral hazard is

a. people drive as carefully in icy conditions with antilock brakes as without b. people drive less safely with more airbags as without c. football players avoid 'spearing' with their heads even with safer helmets d. people read the medicine warnings as carefully when self-medicating versus with a doctor's prescription