AutoParts Co. uses a periodic inventory system and the LIFO method for inventory valuation. The company had the following inventory transactions during December 20X1:

Date	Activity	Units	Unit Cost	Total Cost
Dec. 1	Beginning Inventory	200	$50	$10,000
Dec. 10	Purchase	400	$52	$20,800
Dec. 20	Purchase	300	$55	$16,500
Dec. 31	Ending Inventory	250	-	-

Sales for the month totaled 650 units.

Required:

1. Calculate the cost of goods sold (COGS) and ending inventory using the LIFO method.
2. Prepare the journal entries to record the purchases and sales during December.
3. Discuss the impact of using LIFO on the company’s gross profit and tax liability compared to FIFO.
4. Explain how the periodic inventory system affects the timing of expense recognition in financial statements.