At the beginning of May, Williams Industries has 200 units of a product with a unit cost of $500. Its inventory records report the following transactions for the month of May:

	Units	Unit Cost	Total Cost
Beginning Inventory	200	$500	$100,000
Purchase #1	250	$550	137,500
Purchase #2	100	$600	60,000
Purchase #3	60	$650	39,000
Total	610		$336,500

Williams sells 500 units in May.

a) Compute the Cost of Goods Sold (COGS) for May for this product, assuming Hanna uses FIFO, LIFO, and Average Cost inventory methods.

b) Compute the Ending Inventory Balance (EI) for May for this product, assuming Hanna uses FIFO, LIFO, and Average Cost inventory methods.

c) Assume the total revenue is $350,000, what are the Gross Profit Margin under FIFO, LIFO, and Average Cost methods?