Zambian Co. records show the following purchases and sales for the month of May. Unit Cost $9 Date Beginning Inventory 1 May 10 May Sale 15 May Purchase 24 May Purchase 30 May Sale Units 30 20 22 38 48 $11 $12 Required Compute the ending inventory at 31 May and cost of goods sold using: a) (i) FIFO method under periodic inventory system. (ii) FIFO method under perpetual inventory system. (6 marks) b) (i) Average-cost method under periodic inventory system. (ii) Average-cost method under perpetual inventory system. (8 marks)