4) Inventory cost flow assumptions The following inventory transactions took place for NPR Corporation for the month of May Date May 1 May 5 May 10 May 15 May 20 May 22 May 24 May 25 Event Beginning Inventory Purchase Purchase Sale Sale Purchase Purchase Sale Quantity 1,000 6,000 2,000 3,000 2,000 5,000 2,000 7,000 Cost/Selling Price $3.55 3.10 3.75 6.00 6.00 3.45 3.75 6.00 Instructions Calculate the ending inventory balance for NPR Corporation, assuming the company uses a periodic inventory system and the weighted average cost formula