Inventory shrinkage refers to the loss of inventory due to factors like theft, damage, or administrative errors. Administrative mistakes, such as incorrect data entry or miscounting during stock-taking, lead to discrepancies between recorded and actual inventory levels, which are classified as shrinkage costs because they represent a loss of value or control over assets.

The formula for average stock level is: Minimum Stock Level + (Reorder Quantity / 2). Given the average stock is 9,000 and the minimum stock is 4,000, we set up the equation: 9,000 = 4,000 + (Reorder Quantity / 2). Subtracting 4,000 from both sides gives 5,000 = Reorder Quantity / 2. Multiplying by 2 results in a reorder quantity of 10,000 units. This ensures optimal inventory levels are maintained.

The base stock method involves maintaining a minimum level of inventory at all times to ensure that operations can continue without interruption. This acts as a safety buffer against unexpected demand or supply chain delays, ensuring the business does not run out of essential materials.

The reorder point is calculated by multiplying the lead time by the rate of consumption or sales. In this scenario, 35 minutes multiplied by 400 units per minute equals 14,000 units, which is the threshold at which a new order must be placed to avoid stockouts.

The annual relevant ordering cost is determined by multiplying the total number of purchase orders placed during the year by the cost incurred per individual purchase order. This metric is essential for optimizing inventory management and minimizing total costs.

The cost of goods available for sale represents the total value of inventory that a business could potentially sell during an accounting period. It is calculated by taking the value of the inventory at the start of the period (opening inventory) and adding the net purchases made during that same period. This figure serves as the basis for determining the cost of goods sold after subtracting the closing inventory.

The reorder point is the specific level of inventory at which a new order must be placed to replenish stock before it runs out. It is calculated by multiplying the lead time (the time taken to receive an order) by the average daily or weekly usage rate. This ensures that the business maintains sufficient inventory to meet demand without incurring stockouts.

The reorder point formula relies on the lead time, which is the duration between placing an order and receiving the goods. While the provided option uses the term 'purchase order lease time', it refers to the lead time component. This duration is critical for ensuring that the replenishment order arrives exactly when the safety stock level is reached, preventing production delays.

Materials Requirement Planning (MRP) is a production planning and inventory control system used to manage manufacturing processes. It relies on demand forecasting to schedule production and order materials. Unlike 'pull' systems that respond to actual customer demand, MRP is often categorized as a 'push' system because it initiates production based on projected requirements.

The re-order level is the inventory threshold at which a new order must be placed to replenish stock before it runs out. While the specific data points are missing, the correct answer is identified as 4500 units based on the provided key. This level is typically calculated as Maximum Usage multiplied by Maximum Lead Time.