The Economic Order Quantity (EOQ) is a fundamental formula in inventory management used to calculate the optimal order size that minimizes the sum of ordering costs and holding costs. By balancing these two opposing costs, businesses can achieve maximum efficiency in their inventory procurement processes.

A trading concern purchases finished goods for resale rather than manufacturing them. Therefore, its inventory consists primarily of merchandise inventory, which represents the cost of goods held for sale. Unlike manufacturing firms, trading businesses do not typically hold raw materials or work-in-progress inventory, as they do not engage in production processes.

The standard cost method involves assigning a predetermined cost to inventory items based on efficient production levels and expected costs. This method is widely used for cost control and performance measurement, as it allows management to compare actual costs against the established standards, highlighting variances that require investigation or operational adjustments.

First, calculate the Cost of Goods Sold (COGS) using the inventory turnover formula: COGS = Average Inventory * Turnover Rate = $80,000 * 6 = $480,000. Since the gross profit is 25% of cost, Gross Profit = $480,000 * 0.25 = $120,000. Sales = COGS + Gross Profit = $480,000 + $120,000 = $600,000. This calculation provides the total revenue expected based on inventory movement and markup.

Relevant inventory carrying costs are determined by summing all costs associated with holding inventory over a specific period. By adding the incremental costs of $5,000 to the opportunity cost of capital of $2,500, we arrive at a total carrying cost of $7,500.

Purchasing costs represent the direct financial outlay required to acquire inventory from suppliers. This typically includes the invoice price of the goods, net of any trade discounts, and is a fundamental component of total inventory costs in accounting.