Perpetual systems-assigning costs to inventory
	
	
		Can someone explain this process to me as if I am two. I am not getting this and I don't know why.
Dec 7   310 units @ 3.00 unit cost
Dec 14 20 units @ 3.20
Dec 21 15 units @ 14.00
Trader sells 15 units for 25 dollars each on Dec 15. Eight of the sold units are from ythe Dec 7 purchase and seven are from the Dec 14 purchase. Trader uses a perpetual inventory system. Determine the costs assigned to the Dec 31 ending inventory when costs are assigned based on FIFO, LIFO, weighted average, and specific identification.