Chapter 7: The Costs of Production

HW #7: Solutions
QUESTIONS FOR REVIEW
8. Assume the marginal cost of production is greater than the average variable cost. Can you determine whether the average variable cost is increasing or decreasing? Explain.
If the average variable cost is increasing (decreasing), then the last unit produced is adding more
(less) to total variable cost than the previous units did, on average. Therefore, marginal cost is above (below) average variable cost. In fact, the point where marginal cost exceeds average variable cost is also the point where average variable cost starts to rise.
11. How does a change in the price of one input change the firm’s long-run expansion path?
The expansion path describes the combination of inputs that the firm chooses to minimize cost for every output level. This combination depends on the ratio of input prices: if the price of one input changes, the price ratio also changes. For example, if the price of an input increases, less of the input can be purchased for the same total cost, and the intercept of the isocost line on that input’s axis moves closer to the origin. Also, the slope of the isocost line, the price ratio, changes. As the price ratio changes, the firm substitutes away from the now more expensive input toward the cheaper input. Thus, the expansion path bends toward the axis of the now cheaper input.

EXERCISES
7. The cost of flying a passenger plane from point A to point B is $50,000. The airline flies this route four times per day at 7am, 10am, 1pm, and 4pm. The first and last flights are filled to capacity with 240 people. The second and third flights are only half full. Find the average cost per passenger for each flight. Suppose the airline hires you as a marketing consultant and wants to know which type of customer it should try to attract, the off-peak customer (the