Black Company uses the weighted-average method in its process costing system. company's ending work in process inventory consists of 5,000 units, 80% complete with respect to materials and 50% complete with respect to labour and overhead. If the total dollar value of the inventory is $60,000 and the cost per equivalent unit for labour and overhead is $8.00, the cost per equivalent unit for materials must be?

A) $8.00.
B) $4.00.
C) $10.00.
D) $5.00.

Using the weighted-average method, we can calculate the equivalent units of production for materials, labour, and overhead separately.

Equivalent units of material = Units in ending WIP inventory x Percentage complete with respect to materials
= 5,000 x 80%
= 4,000

Equivalent units of labour and overhead = Units in ending WIP inventory x Percentage complete with respect to labour and overhead
= 5,000 x 50%
= 2,500

Total equivalent units = Equivalent units of material + Equivalent units of labour and overhead
= 4,000 + 2,500
= 6,500

To find the cost per equivalent unit for materials, we can use the following formula:

Cost per equivalent unit = Total cost ÷ Total equivalent units

We are given the total dollar value of the inventory ($60,000) and the cost per equivalent unit for labour and overhead ($8.00).

Total cost = Total equivalent units x Cost per equivalent unit
= 6,500 x $8.00
= $52,000

To find the cost per equivalent unit for materials:

Cost per equivalent unit = Total cost ÷ Total equivalent units
= $52,000 ÷ 4,000
= $13.00

Therefore, the cost per equivalent unit for materials must be $13.00. However, this option is not given in the answer choices. We need to remember that we are asked for the cost per equivalent unit for materials, not the total cost.

Cost per equivalent unit = Total cost ÷ Total equivalent units
Cost per equivalent unit for labour and overhead = $8.00

Total equivalent units = Equivalent units of material + Equivalent units of labour and overhead
Total equivalent units = 6,500

Total cost for labour and overhead = Cost per equivalent unit for labour and overhead x Equivalent units of labour and overhead
Total cost for labour and overhead = $8.00 x 2,500
Total cost for labour and overhead = $20,000

Total cost for material = Total cost - Total cost for labour and overhead
Total cost for material = $60,000 - $20,000
Total cost for material = $40,000

Cost per equivalent unit for material = Total cost for material ÷ Equivalent units of material
Cost per equivalent unit for material = $40,000 ÷ 4,000
Cost per equivalent unit for material = $10.00

Therefore, the cost per equivalent unit for materials is $10.00. The correct answer choice is C.