Final answer:
The four-firm concentration ratio, showing top firm dominance in a market, is 40% for the automotive windshield replacement market, indicating a competitive marketplace. The Herfindahl-Hirschman Index is another measure to assess market competition through market share analysis.
Step-by-step explanation:
The question pertains to the calculation of market concentration ratios in the context of business economics. The four-firm concentration ratio is a measure of market dominance by the top four firms in an industry. It is calculated by adding up the market shares of the four largest firms, and a higher ratio indicates less competition. For the given case of a market for replacing broken automobile windshields, the four-firm concentration ratio is 40%, implying that the largest four firms control less than half of the market, which is not considered a high concentration. The Herfindahl-Hirschman Index (HHI) is another metric used to assess market competition. It is computed by squaring the market shares of all firms and summing these squares, with a higher HHI suggesting a higher level of market concentration.