Shown below is activity for one of the products of Denver Office Equipment: January 1 balance, 500 units @ $55 $27,500 Purchases: January 10: 500 units @ $60 January 20:1,000 units @ $63 Sales: January 12: 800 units January 28: 750 units PROBLEM 1 Required: Compute the January 31 ending inventory and cost of goods sold for January, assuming Denver uses perpetual FIFO. PROBLEM 2 Required: Compute the January 31 ending inventory and cost of goods sold for January, assuming Denver uses LIFO and a perpetual inventory system. PROBLEM 3 Required: Compute the January 31 ending inventory and cost of goods sold for January, assuming Denver uses average cost and a periodic inventory system. PROBLEM 4 Required: Compute the January 31 ending inventory and cost of goods sold for January, assuming Denver uses LIFO and a periodic inventory system