PR 6-3A weighted average cost method with perpetual inventory. the beginning inventory for midnight supplies and data on purchases and sales for a three - month period are shown in problem 6-1A. instruction 1. record the inventory purchase and the cost of goods sold in the perpetual inventory record similar to the one illustrated in Exhibit 5, using the weighted average cost method. 2. determine the total sales, the cost of goods sold, and the gross profit from the sale for the period. 3. determine the ending inventory cost as of march