The debits to Work in ProcessAssembly Department for May, together with data concerning production, are as follows:

May 1, work in process:
Materials cost, 3,000 units	$ 8,000
Conversion costs, 3,000 units, 66.7% completed	6,000
Materials added during May, 10,000 units	30,000
Conversion costs during May	31,000
Goods finished during May, 11,500 units	0
May 31 work in process, 1,500 units, 50% completed	0

All direct materials are placed in process at the beginning of the process and the first-in, first-out method is used to cost inventories. The materials cost per equivalent unit for May is