An industry consists of three firms with sales of $200,000, $500,000, and $400,000.
a. Calculate the Herfindahl-Hirschman index (HHI)
b. Calculate the four-firm concentration ratio (C4)
c. Based on the FTC and DOJ Horizontal Merger Guidelines, do you think the Department of Justice would attempt to block a horizontal merger between two firms with sales of $200,000 and $400,000? Explain.