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?

If the production possibilities frontier of one trade partner ("Country A") is bowed out (concave to the origin), then increased specialization in production by that country will

A) increase the economic welfare of both countries. B) increase the economic welfare of only Country A. C) decrease the economic welfare of Country A. D) decrease the economic welfare of Country B. E) not affect the economic welfare of either country.

If one job applicant truthfully reveals that they subscribe to an industry publication, the job applicant is

A) using the trade publication as a screening tool. B) using the trade publication as a signaling tool. C) using the trade publication as a form of statistical discrimination. D) using the trade publication for the wrong reasons.