please help on all questions

1) The following information is available for a company's maintenance cost over the last seven months. Using the high-low method, estimate both the fixed and variable components of its maintenance cost. Month June July August September October November December Maintenance Hours Maintenance Cost 5,450 6,900 5,100 6,000 6,900 8,100 3,600 2) Which one of the following is an assumption that underlies CVP analysis? 1. For costs classified as variable, the costs per unit of output must change constantly 2. For costs classified as fixed, the costs per unit of output must remain constant. 3- All costs have approximately the same relevant range 4- The selling price per unit must change in proportion to the number of units sold