The isocost line represents all possible combinations of labor and capital that may be purchased for a given total cost. The slope of the isocost line is the ratio of the input prices of labor and capital. If input prices are fixed, then the ratio of these prices is clearly fixed and the isocost line is straight. Only when the ratio or factor prices change as the quantities of inputs change is the isocost line not straight. 5. If the marginal cost of production is increasing, does this tell you whether the average variable cost is increasing or decreasing? Explain. Marginal cost can be increasing while average variable cost is either increasing or decreasing. If marginal cost is less (greater) than average variable cost, then each additional unit is adding less (more) to total cost than previous units added to the total cost, which implies that the AVC declines (increases). Therefore, we need to know whether marginal cost is greater than average variable cost to determine whether the A