Final answer:
The equivalent unit cost for September using the weighted average method is $5.50 per unit.
Step-by-step explanation:
The weighted average method is used to calculate the equivalent unit cost. The formula for the equivalent unit cost is as follows:
Equivalent Unit Cost (EUC) = Total Cost / Equivalent Units
In this case, the total cost is $550,000 (manufacturing costs incurred in September) and the equivalent units are 100,000 (units in BWIP for September).
EUC = $550,000 / 100,000 = $5.50 per unit
Therefore, the equivalent unit cost for September using the weighted average method is $5.50 per unit.