An industry with twenty companies but the CR = 80 percent is called "high concentration", for a concentration ratio of 80 to 100% is viewed as high concentration. Government regulators are usually most concerned with industries falling into this category. It is a good indication of oligopoly and that these four firms have significant market control.
Answers Needed to these:
What are some reasons why this industry has a high CR while the other industry has a low CR?
IS it possible for smaller firm to thrive and profit in such an industry? How?
Contrast the effects efficiency if the dominating firms use a price leadership model versus a contestable markets model.