Lost units; cost of production summaries Monterrey Products Co. uses the process cost system. A record of the factory operations for the month of October follows: Required: Prepare a cost of production summary, assuming that the production losses are considered to be normal. Lost units; cost of production summaries Monterrey Products Co. uses the process cost system. A record of the factory operations for the month of October follows: Required: Prepare a cost of production summary, assuming that the production losses are considered to be normal