The ledger of American Company has the following work in process account. Production records show that there were 550 units in the beginning inventory, 30% complete, 1, 620 units started, and 1, 550 units transferred out. The beginning work in process had materials cost of $2, 740 and conversion costs of $1, 050. The units in ending inventory were 40% complete. Materials are entered at the beginning of the painting process. How many units are in process at May 31? (b) What is the unit materials cost for May