第1个回答 2013-10-14
In an industry where a natural monopoly does not exist, the vast majority of industries, the marginal cost decreases with economies of scale, then increases as the company has growing pains. A natural monopoly has a very different cost structure. A natural monopoly has a high fixed cost for a product that does not depend on output, since average total cost = total cost(fixed+variable cost)/total output, and fixed cost is much higher than variable cost, to an extent which variable cost can be neglectable, so it's an easy math problem as numerator stays the same, denominator increases, the result decrease. For the same reason, the marginal cost is the change of total cost caused by producing one more unit of product, for example, you invest $1000 to produce condom, with one more production of condom, your cost increase $0.5. So no matter you produce how many condom, your marginal cost, the cost of producing one more, is always $0.5, while your average total cost changes dramatically. If you produce only one condom, the average cost is $1000.5, but if you produce 100,000, it drops to $0.51.