Five-gallon i.e 128 ounces stainless steel containers are filled with soft drink syrup on an automatic machine. The filling process is monitored by X and R charts, based on samples of size six. These charts indicate that the process is in control, and the center line of the R chart is 0.20 fluid ounces. The filled containers are inspected, and all underfilled container are rejected. A container is sold for $10; however, an underfilled container must be refilled to correct volume. The additional labor cost associated with this refilling operation is $2. The product cost is $0.10 per fluid ounce. What is the optimum mean target level for the filling machine?