A total of 29 units were started, and 4 spoiled units were detected and rejected at final inspection, yielding 25 good units. the spoild units were considered to be normal spoilage. costs assigned prior to the inspection point are 1000 per unit. The current disposal price of the spoiled units is $205 per unit. when the spoilage is detected the spoiled goods are inventoried at $205 per unit.
What is the normail spoilage rate?