Lewis Company uses weighted average process costing system. Material is added at the start of production. Lewis Company started 13,000 units into production and had 4,500 units in process at the start of the period that were 60 percent complete as to conversion costs. If Lewis Company transferred out 11,750 units, how many units were in ending Work in Process Inventory? a) 1,250 b) 3,000 c) 3,500 and d) 5,750