Relevant Range Review Question The relevant range is: a. The range of activity in which variable costs will be curvilinear. b. The range of activity in which fixed costs will be curvilinear. c. The range over which the company expects to operate during a year: d. Usually from zero to 100% of operating capacity. High-Low Method Assumed Maintenance Costs and Mileage Data Illustration: Metro Transit Company has the following maintenance costs and mileage data for its fleet of buses over a 6month period