4. In its first month of operations, Weatherall Company uses a periodic inventory system and made three purchases of merchandise in the following sequence: (1) 300 units at $6, (2) 400 units at $7, and (3) 200 units at $8. Assuming there are 380 on hand, compute the cost of ending inventory under (a) First-in, First-out (FIFO) method (b) Last-in. First-out (LIFO) method (c) Weighted Average method