The Assembly Department of Interface, Inc., manufacturer of computers, had 4500 units of beginning inventory In September, and 8000 units were transferred to it from the Production Department. The Assembly Department completed 4000 units during the month and transferred them to the Packaging Department. The weighted average method is used. Calculate the total number of units to account for by the Assembly Department. 12,500 units 8000 units 3500 units 4500 units