Answer:
Retained earnings  26,000 debit
     Inventory            26,000 credit
--to adjust for change of method--
Average cost per unit $49
COGS: Â Â Â Â Â Â Â Â 11,000 units x $ 49 = Â 539,000
Ending Inventory 8,500 units x $ 49 = Â 416,500
Explanation:
Beginning inventory, FIFO (6,500 units @ $45.00) $ 292,500
Beginning inventory Average                  $ 266,500 Â
Difference between methods                     26,000
We will adjust inventory against retained earnings as a lower or higher inventory will represent higher or lower COGS respectively
beginning inventory       $ 266,500
Purchases:
6,500 units @ $51.00 Â $ 331,500
6,500 units @ $55.00 $ 357,500
                        689,000
Total good avilable for sale: Â 955,500
Units available for sale: Â Â Â Â Â Â Â 19,500 Â Â
Average cost per unit: 955,500 / 19,500 = $ 49
COGS: 11,000 x $ 49 = 539,000
Ending Inventory 8,500 x $ 49 = Â 416,500