Current Attempt in Progress REI sells snowboards. Assume the following information relates to REI's purchases of snowboards during September. During the same month, 106 snowboards were sold. REI uses a periodic inventory system. Date Explanation Units Unit Cost Total Cost Sept. 1 Inventory 15 $100 $1,500 Sept. 12 Purchases 42 103 4,326 Sept. 19 Purchases 57 104 5,928 Sept. 26 Purchases 21 105 2,205 Totals 135 $13.959 (a) Your answer is correct. Compute the ending inventory at September 30 using FIFO, LIFO, and average-cost. (Round average cost per unit to 3 decimal places, e.g. 125.153 and final answers to 0 decimal places, e.g. 125.) (b) Compute the cost of goods sold for the month using the FIFO, LIFO, and average-cost