To solve this problem using the FIFO (First-In, First-Out) method under the perpetual inventory system, let's break down the steps:

1. Beginning Inventory (January 1):

   • 320 units at $3.00 per unit = $960.

2. First Purchase (January 9):

   • 80 units at $3.20 per unit = $256.

3. Second Purchase (January 25):

   • 100 units at $3.34 per unit = $334.

4. Total Inventory Before Sale (on January 25):

   • 320 units at $3.00 = $960
   • 80 units at $3.20 = $256
   • 100 units at $3.34 = $334
     Total units: 500 units
     Total cost: $1,550

5. Units Sold on January 26:
   The company sells 350 units on January 26. Since this is FIFO, we sell the oldest inventory first.

   • From the beginning inventory (320 units at $3.00 per unit), we sell all 320 units:
     • 320 units × $3.00 = $960.
   • From the January 9 purchase (80 units at $3.20 per unit), we sell 30 units:
     • 30 units × $3.20 = $96.

   Total cost of goods sold (COGS): $960 + $96 = $1,056.

6. Ending Inventory (after sale):
   After selling 350 units, we are left with 150 units in inventory, consisting of:

   • 50 units from the January 9 purchase at $3.20 = 50 units × $3.20 = $160.
   • 100 units from the January 25 purchase at $3.34 = 100 units × $3.34 = $334.

   Total cost of ending inventory: $160 + $334 = $494.

Answer:

The costs assigned to the ending inventory on January 31, using the FIFO method, are $494.

Would you like more details or have any questions?

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Here are five related questions you might find interesting:

1. How would the cost assigned to ending inventory change using the LIFO method?
2. What is the impact of the weighted-average cost method on the ending inventory?
3. How does the perpetual inventory system differ from the periodic system in FIFO?
4. What effect does FIFO have on net income during periods of rising prices?
5. How does inventory turnover ratio relate to FIFO?

Tip: FIFO is often preferred in times of inflation as it results in lower cost of goods sold (COGS) and higher net income.