Isotonic Aluminum Company uses a process cost system to record the costs of manufacturing rolled aluminum, which requires a series of four processes. The inventory of Work in Process—Rolling on September 1, 2006, and debits to the account during September were as follows:
Bal., 4,500 units, 1/3 completed:
Direct materials (4,500 x $38.60) ......... $173,700
Conversion (4,500 x 1/3 x $11.74) ........ 17,610
$191,310
From Smelting Dept., 160,000 units ........ 6,200,000
Direct labor ................... 765,600
Factory overhead ................ 1,146,000
During September, 4,500 units in process on September 1 were completed, and of the 160,000 units entering the department, all were completed except 5,000 units that were 4/5 completed.
Charges to Work in Process—Rolling for October were as follows:
From Smelting Department, 175,000 units ...... $6,797,000
Direct labor .................. 826,080
Factory overhead .................. 1,239,120
During October, the units in process at the beginning of the month were completed, and of the 175,000 units entering the department, all were completed except 6,500 units that were 2/5 completed.

Instructions
1. Enter the balance as of September 1, 2006, in a four-column account for Work in Process—Rolling. Record the debits and the credits in the account for September. Construct a cost of production report and present computations for determining (a) equivalent units of production for materials and conversion, (b) equivalent costs per unit, (c) cost of goods finished, differentiating between units started in the prior period and units started and finished in September, and (d) work in process inventory.
2. Provide the same information for October by recording the October transactions in the four-column work in process account. Construct a cost of production report, and present the October computations (a through d) listed in (1).
3. Comment on the change in cost per equivalent unit for August through October for direct materials and conversion cost.