Custom's has three cost pools and an associated cost driver to allocate the costs to the product. The cost pools, cost driver, estimated overhead, and estimated activity for the cost pool are:

Cost Pool	Cost Driver	Estimated Activity per Driver	Estimated Overhead
Material	Material requisitions	14,000	$ 52,500
Machining	Machine hours	186,400	363,500
Inspection	Number of inspections	10,000	75,000

Which activity has the highest predetermined overhead rate?