Current Attempt in Progress Sandhill Co. uses a periodic inventory system. Its records show the following for the month of May, in which 79 units were sold. (a) Your answer is correct. Calculate the weighted-average unit cost. (Round answer to 3 decimal places, e.g. 5.125.) Weighted-average unit cost $ eTextbook and Media Attempts: 1 of 5 used (b) Calculate the ending inventory at May 31 using the FIFO, LIFO and average-cost methods. (Round answers to 0 decimal places, e.g. 125.)