The debits to Work in Process--Assembly Department for April, together with data concerning production, are as follows: April 1, work in process: Materials cost, 3,000 units $ 7,200 Conversion costs, 3,000 units, 40% completed 6,000 Materials added during April, 10,000 units 25,000 Conversion costs during April 30,800 Goods finished during April, 12,000 units --- April 30 work in process, 1,000 units, 40% completed --- 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 conversion cost per equivalent unit for April is: a. $2.48 b. $2.75 c. $2.50 d. $5.25