To calculate the equivalent units of work done for direct materials during January, we need to account for both the units completed and transferred out as well as the units still in process at the end of the period.

Step 1: Identify key data

• Started during January: 90 physical units
• Opening work in process (January 1): 10 physical units
• Completed during January: 80 physical units
• Closing work in process (January 31): 20 physical units
• Degree of completion (direct materials):
  • Opening work in process: 100%
  • Closing work in process: 90%

Step 2: Calculate the equivalent units for direct materials

1. Units completed and transferred out:

These units are fully completed in terms of direct materials (100%). The number of units completed during January is 80 units.

• Equivalent units for direct materials: 80 * 100% = 80 units

2. Units in closing work in process:

The closing work in process (20 units) is 90% complete with respect to direct materials.

• Equivalent units for direct materials in closing WIP: 20 * 90% = 18 units

3. Units in opening work in process:

The opening work in process (10 units) is already 100% complete for direct materials, so no additional work is needed.

• Equivalent units for direct materials in opening WIP: 10 * 100% = 10 units

Step 3: Total equivalent units for direct materials

To calculate the total equivalent units of work done for direct materials in January, sum the equivalent units from the completed units, opening WIP, and closing WIP:

$\text{Total equivalent units for direct materials} = 80 + 18 + 10 = \boxed{108 \text{ units}}$

Final Result:

The equivalent units of work done for direct materials during January is 108 units.

Would you like further clarification or help with a related topic?

5 related questions:

1. How do you calculate equivalent units for conversion costs?
2. What is the difference between work in process and finished goods in process costing?
3. How are the cost per unit for direct materials calculated in process costing?
4. How does the degree of completion affect the calculation of equivalent units?
5. What is the purpose of using equivalent units in process costing?

Tip:

When calculating equivalent units for incomplete units in process, remember to always factor in the degree of completion.