Check my worl An industry consists of three firms with sales of $235,000, $680,000, and $315,000. a. Calculate the Herfindahl-Hirschman index (HHI). Instruction: Enter your response rounded to the nearest integer. b. Calculate the four-firm concentration ratio (C4 c. Based on the FTC and DOJ Horizontal Merger Guidelines described in the text, is the Department of Justice likely to attempt to block a horizontal merger between two firms with sales of $235,000 and $315,000? O Yes O No