The debits to Work in Process-Assembly Department for May, together with data concerning production, are as follows: May 1, work in process: Materials cost, 3,000 units $8,700 Conversion costs, 3,000 units, 50% completed 5,900 Materials added during May, 10,000 units 26,200 Conversion costs during May 35,000 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 Oa. $2.62 Ob. $2.28 Oc. $3.50 Od. $4.37