4) Mardon Tool & Die Company - in chronological order, the inventory, purchases and sales of a single product for a recent month are as follows: Units Amount per Unit June 1 Beginning Inventory 150 $30 4 Purchases 400 $33 12 Purchases 800 $36 16 Sale 1,300 $60 24 Purchases 300 $39 a) Computer the cost of ending inventory, cost of goods sold and gross margin. Use the Average cost, FIFO and LIFO Inventory Methods