Particular relationship between marginal cost and the two-order-per-unit cost measures that is not as evident in Table 7.2 Notice that when marginal cost is equal to average variable cost, the latter measure is at its minimum point. (This occurs at 4 units of output) When marginal cost is equal to average cost, average cost is at its minimum point. (This occurs at 6 units of output.) Another way to describe these relationships is to state that as long as marginal cost is below average variable cost, average variable cost declines as output increases. However, when marginal cost exceeds average variable cost, average variable cost starts to increase. The same relationship holds between marginal cost and average total cost. The economic significance of these relationships is explained in chapter 9. But for now, it is important at least to note these relationships among the different per-unit measures of cost. Summarizing these relationships in abbreviated form: