$7000. 4,000 units of direct materials were added during the period at a cost of $8200. 4,500 units were completed during the period, and 500 units were 60% complete at the end of the period. all materials are added at the beginning of the process. direct labor was 28,700 and factory overhead was $4,510. what was the cost of 500 units in process at the end of the period (assuming first in fist out method