Identify which of the following manufacturing overhead costs are value-added and which are non-value-added.
1. Moving raw materials from the receiving area to the storage area.
2. Storing raw materials until needed in production.
3. Inspecting raw materials when they arrive to make sure that they meet specifications.
4. Assembling parts into a completed product.
5. Partially completed units are stacked while awaiting the next production step.
6. Some of the raw materials are broken while in storage.
7. Product warranty work is performed on units that malfunctioned for customers.
8. Product is delivered to customer.