Answer:
a. FIFO COGS $ 17640
a. FIFO Ending Inventory $ 12960  
b. LIFO  COGS $ 19160
b. LIFO ending Inventory $ 11440
c. Weighted COGS   $ 18360
c.Weighted Ending Inventory $12240
Explanation:
Cortez Company
Particulars                    Units       unit Cost           Total Cost
Opening Inventory       100              $ 60              $ 6000
Purchases                     150               $ 68             10200
<u>Batch 2                          200              $ 72              $ 14400</u>
<u>Total                           450                                        $30600    </u>
FIFO means first units received will be sold out first and the ending inventory consists of last units.
Sales = 270 units 
a. FIFO COGS $ 17640
100   units at   $ 60 =  $ 6000
 150  units at   $ 68 = 10200
20  units at $ 72 = $1440
a. FIFO Ending Inventory $ 12960  
 180  units at $ 72  =$ 12960  
LIFO means last units received will be sold out first and the ending inventory consists of first units.
b. LIFO  COGS $ 19160
200 units at $ 72 = $ 14400
70 units at $ 68  = 4760
b. LIFO ending Inventory $ 11440
 100  units at  $ 60= $ 6000
 80   units at   $ 68 = 5440
c. Weighted Average Cost = Total Cost/ No of units = $30600  /450= $ 68
c. Weighted COGS = 270 units at $ 68=  $ 18360
c. Weighted Ending Inventory= (Total Units - Sales) CP per unit
= (450- 270)* 68
 = 180 *68= $12240