7. Lucas Corporation uses the weighted-average method in its process costing system. Data concerning the first processing department for the most recent month are listed below: Beginning work in process inventory: Units in beginning work in process inventory Materials costs Conversion costs Percent complete with respect to materials Percent complete with respect to conversion Units started into production during the month Units transferred to the next department during the month Materials costs added during the month Conversion costs added during the month Ending work in process inventory: Units in ending work in process inventory 900 S 9,600 S 7,700 60 % 45 % 8,100 6,900 s 115,800 120,500 2,100 Percent complete with respect to materials 75% Percent complete with respect to conversion 20% The cost of ending work in process inventory in the first processing department according to the company's cost system is closest to: a) $13,570 b) S30,660 c) $50,888 d) $67,851