Worksheet Answers – Chapter 32 | 第32章练习题答案

📚 Worksheet Answers – Chapter 32: Inventory Management | 第32章 存货管理 练习题答案

This article provides detailed worksheet answers for Chapter 32 on Inventory Management, a key topic in Cambridge A-Level Business. Each question is answered with step-by-step explanations to reinforce understanding of inventory control, costs, and modern techniques like Just-in-Time.

本文提供剑桥A-Level商务第32章存货管理的详细练习题答案。每个问题都配有逐步解释，帮助加深对库存控制、成本以及准时制等现代方法的理解。

1. Economic Order Quantity (EOQ) Calculation | 经济订货批量计算

Question: A business sells 36,000 units of a product each year. The cost of placing one order is $50, and the annual holding cost per unit is $2.50. Calculate the Economic Order Quantity.

问题：某企业每年销售36,000件产品。每次订购成本为50美元，每单位年持有成本为2.50美元。计算经济订货批量。

Answer: The EOQ formula is: EOQ = √(2 × D × Co ÷ Ch) where D = annual demand, Co = ordering cost per order, Ch = holding cost per unit per year. Substituting the values: EOQ = √(2 × 36,000 × $50 ÷ $2.50) = √(3,600,000 ÷ 2.5) = √1,440,000 = 1,200 units.

答案：EOQ公式为：EOQ = √(2 × D × Co ÷ Ch)，其中D为年需求量，Co为每次订购成本，Ch为单位产品年持有成本。代入数值：EOQ = √(2 × 36,000 × $50 ÷ $2.50) = √(3,600,000 ÷ 2.5) = √1,440,000 = 1,200 件。

Explanation: EOQ minimizes total inventory costs by balancing ordering and holding costs. At 1,200 units per order, the business will place 30 orders per year (36,000 ÷ 1,200), resulting in equal ordering and holding costs of $1,500 each, giving a minimum total of $3,000.

说明：EOQ通过平衡订购成本与持有成本使总库存成本最小化。每次订购1,200件时，企业每年订购30次（36,000 ÷ 1,200），订购成本与持有成本各为1,500美元，最小总成本为3,000美元。

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2. Reorder Level and Safety Stock | 再订货水平与安全库存

Question: Daily demand is 100 units, lead time is 4 days, and the business keeps safety stock of 200 units. Calculate the reorder level.

问题：每日需求量为100件，前置期为4天，企业保有200件安全库存。计算再订货水平。

Answer: Reorder level = (daily demand × lead time) + safety stock = (100 × 4) + 200 = 600 units. When inventory falls to 600 units, a new order should be placed to avoid stockouts.

答案：再订货水平 = （每日需求量 × 前置期）+ 安全库存 = （100 × 4）+ 200 = 600 件。当库存降至600件时，即应下新订单以免缺货。

Safety stock of 200 units protects against unexpected demand surges or supply delays. Without it, reorder level would be only 400 units, increasing the risk of running out of stock.

200件的安全库存用于应对意外的需求激增或供应延迟。如果没有安全库存，再订货水平仅为400件，缺货风险将上升。

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3. Total Inventory Cost at EOQ | EOQ下的总库存成本

Question: Using the results from Question 1, calculate total annual ordering cost and total annual holding cost, and prove that they are equal at the EOQ.

问题：利用第1题的结果，计算年总订购成本和年总持有成本，并证明在EOQ下二者相等。

Answer: Number of orders per year = 36,000 ÷ 1,200 = 30 orders. Total ordering cost = 30 × $50 = $1,500. Average inventory = 1,200 ÷ 2 = 600 units. Total holding cost = 600 × $2.50 = $1,500. Both are equal, confirming the EOQ.

答案：每年订购次数 = 36,000 ÷ 1,200 = 30 次。总订购成本 = 30 × $50 = $1,500。平均库存 = 1,200 ÷ 2 = 600 件。总持有成本 = 600 × $2.50 = $1,500。二者相等，验证了EOQ的正确性。

If the order quantity deviates from 1,200 units, the two costs will no longer be equal, and total cost will rise. For example, ordering 2,000 units per order increases holding cost more significantly than it reduces ordering cost.

若订货量偏离1,200件，两项成本将不再相等，总成本会上升。例如，每次订购2,000件将使持有成本大幅增加，超过订购成本所节省的金额。

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4. Just-in-Time (JIT) Inventory Management | 准时制库存管理

Question: Explain two advantages and two disadvantages of a Just-in-Time inventory system for a car manufacturer.

问题：解释汽车制造商采用准时制库存系统的两个优点和两个缺点。

Answer: Advantages:

• Reduces waste and storage costs because materials arrive only when needed.
• 减少浪费和仓储成本，因为材料仅在需要时才到达。
• Improves cash flow by minimizing money tied up in inventory.
• 降低库存占用的资金，从而改善现金流。

Disadvantages:

• Heavy reliance on suppliers; any delivery delay can halt production.
• 高度依赖供应商；任何交货延迟都可能导致生产停滞。
• No buffer stock to meet sudden increases in demand, risking lost sales.
• 无缓冲库存应对突发需求，存在丢失销售机会的风险。

JIT suits manufacturers with stable demand and reliable supply chains. For a car manufacturer, close coordination with component suppliers is essential to avoid assembly line stoppages.

JIT适用于需求稳定且供应链可靠的生产商。对于汽车制造商来说，与零部件供应商的紧密协调对于避免装配线停工至关重要。

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5. Inventory Turnover Ratio | 库存周转率

Question: A retailer reports cost of goods sold of $480,000 and average inventory of $80,000. Calculate the inventory turnover ratio and comment on its efficiency.

问题：某零售商报告的销货成本为480,000美元，平均库存为80,000美元。计算库存周转率并评价其效率。

Answer: Inventory turnover = Cost of goods sold ÷ Average inventory = $480,000 ÷ $80,000 = 6 times per year. This means the business sells and replaces its inventory six times annually.

答案：库存周转率 = 销货成本 ÷ 平均库存 = $480,000 ÷ $80,000 = 6次/年。这意味着该企业每年销售并更换库存6次。

A higher turnover generally indicates efficient inventory management and strong sales. However, an excessively high ratio could signal frequent stockouts. In retail, 6–8 times is often acceptable, depending on the industry.

较高的周转率通常意味着库存管理高效且销售强劲。但过高的比率可能表明频繁缺货。在零售业，6至8次通常是可接受的，具体视行业而定。

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6. Purpose of Buffer Stock | 缓冲库存的目的

Question: Why do businesses hold buffer stock? Use a clothing retailer as an example.

问题：企业为何要保持缓冲库存？请以服装零售商为例。

Answer: Buffer stock is the minimum inventory level held to prevent stockouts caused by unexpected demand or supply disruptions. A clothing retailer, for example, maintains buffer stock of basic items like plain T-shirts because demand can surge during a heatwave. If a supplier is late delivering the next batch, the buffer stock covers sales during the delay, protecting customer loyalty.

答案：缓冲库存是为防止意外需求或供应中断导致缺货而保持的最低库存水平。例如，服装零售商会保持像纯色T恤这类基础款产品的缓冲库存，因为在热浪来袭时需求可能激增。如果供应商下一批货延迟交付，缓冲库存可在延迟期内保障销售，维护客户忠诚度。

Without buffer stock, the retailer risks empty shelves, lost revenue, and a damaged reputation. The buffer level is determined by the variability of demand and supplier reliability.

没有缓冲库存，零售商可能面临空货架、收入损失和声誉受损。缓冲水平的确定取决于需求波动性和供应商可靠性。

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7. Interpreting an Inventory Control Chart | 解读库存控制图

Question: Describe the key levels on a typical inventory control chart: maximum stock, reorder level, minimum (buffer) stock, and lead time.

问题：描述典型库存控制图上的关键水平：最大库存量、再订货水平、最小（缓冲）库存量以及前置期。

Answer: An inventory control chart tracks stock levels over time. Maximum stock is the highest quantity held, often limited by storage space or cost. Reorder level is the point at which a new order is triggered; stock must be enough to cover lead-time demand plus safety stock. Minimum stock (buffer) is the emergency reserve to avert stockouts. Lead time is the period between placing an order and receiving it. The chart shows a sawtooth pattern: stock depletes, hits reorder level, a new order is placed, and during lead time stock continues falling until the delivery raises it back to maximum.

答案：库存控制图追踪库存水平随时间的变化。最大库存量是所持的最高数量，通常受仓储空间或成本限制。再订货水平是触发新订单的点；库存必须足以覆盖前置期内的需求加上安全库存。最小库存（缓冲）是避免缺货的应急储备。前置期是从下订单到收货的时间段。图表呈现出锯齿状模式：库存消耗至再订货水平时下新订单，在前置期内库存继续下降，直到到货将库存拉回最大水平。

Understanding these levels helps managers avoid overstocking (high holding costs) or understocking (stockouts). The reorder level is calculated as lead time demand plus buffer stock.

理解这些水平有助于管理者避免过度库存（高持有成本）或库存不足（缺货）。再订货水平计算公式为：前置期需求量 + 缓冲库存。

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8. Impact of Supplier Reliability on Inventory Decisions | 供应商可靠性对库存决策的影响

Question: Evaluate how poor supplier reliability affects the inventory management of a smartphone assembler.

问题：评估供应商可靠性差对智能手机组装商库存管理的影响。

Answer: Poor supplier reliability — such as frequent late deliveries or inconsistent quality — forces a business to increase buffer stock and reorder levels, raising holding costs. The smartphone assembler may need to invest in more warehouse space and tie up capital in additional component inventory. It might also consider dual sourcing or switching to more reliable suppliers, even if unit costs are higher, to ensure production continuity.

答案：供应商可靠性差——例如频繁延迟交货或质量不稳定——会迫使企业增加缓冲库存和再订货水平，从而抬高持有成本。智能手机组装商可能需要投资更多仓储空间，并将资金占用在额外的零部件库存上。企业还可能考虑双源采购或转向更可靠的供应商，哪怕单位成本更高，以确保生产连续性。

Conversely, high supplier reliability allows lower safety stock, reducing costs and enabling lean inventory methods like JIT. Thus, supplier relationships directly shape inventory strategy and operational efficiency.

相反，高供应商可靠性允许降低安全库存，减少成本，并实现像JIT这样的精益库存方法。因此，供应商关系直接塑造库存战略和运营效率。

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9. Limitations of the EOQ Model | 经济订货批量模型的局限性

Question: State two assumptions of the EOQ model that may not hold in reality and explain their implications.

问题：指出EOQ模型的两个在现实中可能不成立的假设，并解释其影响。

Answer: Two key assumptions are:

• Constant and known demand – in reality, demand fluctuates due to seasons, trends, or economic shifts, making the EOQ less accurate.
• 需求恒定且已知——现实中，需求因季节、趋势或经济变化而波动，这降低了EOQ的准确性。
• Fixed ordering and holding costs – these costs can change with bulk discounts, inflation, or changes in storage rates, distorting the optimal quantity.
• 订购成本和持有成本固定不变——这些成本可能因批量折扣、通货膨胀或仓储费率变化而变动，从而扭曲最优订货量。

Because of these limitations, managers often use EOQ as a guide rather than a strict rule, adjusting for real-world conditions with judgment and additional safety stock.

由于这些局限性，管理者常将EOQ作为指导而非严格规则，结合判断和额外的安全库存以适应现实条件。

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10. Comparing Stock Valuation Methods: FIFO vs. LIFO | 存货估值方法比较：先进先出法与后进先出法

Question: In a period of rising prices, compare the impact of FIFO and LIFO on reported profit and inventory value for a business.

问题：在物价上涨期间，比较先进先出法（FIFO）和后进先出法（LIFO）对企业报告利润和存货价值的影响。

Answer: Under FIFO (First-In-First-Out), older, cheaper inventory is charged to cost of goods sold, so profit appears higher and ending inventory is valued at recent higher prices. Under LIFO (Last-In-First-Out), newer expensive inventory is matched against revenue, reducing reported profit and resulting in a lower ending inventory value that is based on older, cheaper costs.

答案：在FIFO下，较旧、较便宜的存货先计入销货成本，因此利润显得更高，期末存货按近期较高价格估价。在LIFO下，较新、较贵的存货与收入匹配，降低了报告利润，导致期末存货价值较低，因其基于较早、较便宜的成本。

In taxation, LIFO can reduce taxable income in inflationary times, but many accounting standards (like IFRS) do not permit LIFO. Managers must understand these effects when analyzing profitability and asset values.

在税务方面，通货膨胀时LIFO可减少应税收入，但许多会计准则（如IFRS）不允许使用LIFO。管理者在分析盈利能力和资产价值时必须了解这些影响。

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