Use the following information for questions 12, 13, and 14. Pederson Company was formed on December 1, 2015. The following information is available from Pederson's inventory records for the product X:

Date	Purchases	Sold/Issued	Balance
12/2	2000 units @ $4.00/unit		2,000
12/15	6000 units @4.40/unit		8000
12/19		4000 units	4000
12/30	2000 units @ 4.75/unit		6000

11. Assuming that Pederson uses a perpetual inventory system, what is ENDING INVENTORY at December 31, 2015 under the FIFO method? a. $18,100 b. $27,100 c. $16,800 d. $13,800 e. None of the above

12. Assuming that Pederson uses a perpetual inventory system, what is ENDING INVENTORY at December 31, 2015 under the LIFO method? a. $18,300 b. $17,600 c. $26,300 d. $25,600 e. None of the above

13. Assuming that Pederson uses a periodic inventory system, what is ENDING INVENTORY at December 31, 2015 under the weighted average method? a. $17,200 b. $26,700 c. $17,560 d. $26,340 e. None of the above

I have the answers, just don't understand the concepts so work is appreciated!

Thanks!