7.3
总固定成本曲线、总可变成本曲线与总成本曲线
在短期内，企业会承担多种固定支出，例如租赁费用、保险费以及设备折旧。这些支出统称为生产的总固定成本（TFC）。在图形上，总固定成本表现为一条与横轴平行的直线，其中纵轴表示成本，横轴表示产出数量。
可变成本包括随产出水平变化的费用，例如所用材料和按小时支付工资的工人工资。这些成本的总和称为总可变成本（…
考虑一家生产桌子的小型企业。在短期内，该企业会产生固定成本，包括工厂租金和机器维护费用。这些成本的总和称为总固定成本或 TFC。
从图形上看，总固定成本（TFC）是一条与横轴平行的水平线，因其不随产量变化而保持不变。
可变成本包括木材费用和按日计酬的劳动力支出。这些成本的总和即为总可变成本（TVC）。
在未进行生产时，总可变成本（TVC）为零。随着制造开始，由于产生了木材和劳动力的成本，总可变成本随之增加。在产出的初始阶段，由于劳动的边际产量递增，总可变成本以递减的速度上升。然而，随着产出进一步增加，劳动的边际产量最终开始递减，导致总可变成本以递增的速度上升。在此产出范围内，工人可能会因等待使用有限的机械设备而处于闲置状态，从而导致生产效率降低。
总成本（TC）是总固定成本（TFC）与总可变成本（TVC）之和。TC 的变化趋势与 TVC 相似，二者曲线相互平行。然而，TC 从总固定成本的数值起点开始，因为这部分成本无论产出如何都会发生。
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Q1: What is total fixed cost and why does it remain constant on a cost curve?
Total fixed cost (TFC) represents expenses a firm incurs regardless of output level, such as factory rent and machine maintenance. Graphically, TFC appears as a horizontal line parallel to the x-axis because these costs remain constant whether the firm produces zero units or maximum capacity. This unchanging nature distinguishes fixed costs from variable expenses.
Q2: How does total variable cost behave as production increases?
Total variable cost (TVC) starts at zero when no production occurs and increases as output rises. Initially, TVC increases at a diminishing rate due to increasing marginal product of labor. Later, TVC rises at an accelerating rate when diminishing marginal product of labor sets in, as workers become idle waiting for limited machinery access, reducing overall productivity.
Q3: What expenses are included in total variable cost for a manufacturing firm?
Total variable cost (TVC) includes all expenses that change with production levels, such as raw materials like wood and hourly wage labor payments. These costs directly correlate with output quantity—the more a firm produces, the higher its variable costs become, making them distinct from fixed expenses like rent.
Q4: How is total cost calculated and why is it parallel to the total variable cost curve?
Total cost (TC) equals the sum of total fixed cost (TFC) and total variable cost (TVC). The TC curve is parallel to the TVC curve because the vertical distance between them—the fixed cost—remains constant across all output levels. TC simply shifts the TVC curve upward by the amount of fixed costs incurred.
Q5: Why does the total cost curve start above the origin on a graph?
The total cost curve starts above the origin because it begins at the total fixed cost point. Even when production is zero, the firm still incurs fixed expenses like rent and machine maintenance. This starting point reflects costs the firm must pay regardless of whether any output is produced.
Q6: What causes the shape of the total variable cost curve to change from gentle to steep?
The TVC curve's shape reflects labor productivity changes. Initially, increasing marginal product of labor causes TVC to rise gently at a lower rate. As production expands, diminishing marginal product of labor emerges, causing TVC to rise steeply. Workers experience idle time waiting for limited machinery, reducing efficiency and increasing costs per unit produced.
Q7: How do fixed and variable costs differ in their relationship to production output?
Fixed costs remain constant regardless of output level, while variable costs change directly with production quantity. Fixed costs like rent and machine maintenance are unavoidable short-run expenses, whereas variable costs such as materials and labor scale with production volume. Understanding this distinction is essential for analyzing cost behavior and profitability.