31. So long as they can more than cover their variable costs , they keep on producing. 32. The level of variable cost is influenced by many factors, such as fixed cost, discount rate. 33. For example, variable manufacturing overhead costs are variable costs that are indirect costs, not direct costs. 34. However, not all variable costs are direct costs. 35. The economy will have to incur more variable costs , such as overtime, to produce the unit. 36. Variable costs are sometimes called unit-level costs as they vary with the number of units produced.37. Variable costs are fixed on a percentage basis.38. The cost of material is a variable cost . 39. Variable costs as a percentage of sales are equal to 100 % minus the contribution margin ratio.40. The rule is conventionally stated in terms of price ( average revenue ) and average variable costs .
