4. Williams Optical Inc. is considering a new lean product cell. The present manufacturing approach produces a product in four separate steps. The present production batch sizes are 40 units. The process time for each step is as follows: The time required to move each batch between steps is 4 minutes. In addition, the time to move from raw materials to Process Step 1 is also 4 minutes, and the time to move completed units from Process Step 4 to finished goods inventory is 6 minutes. The new lean layout will allow the company to reduce the batch sizes from its present quantity of 40 units to a proposed batch of 4 units. The time required to move each proposed batch between steps and the inventory locations will be reduced to 2 minutes. The processing time in each step will stay the same. Determine the: - value-added lead time, - non-value-added lead time, - total lead time, - the value-added ratio (Round percentages to two spaces behind the decimal.) under the following batch sizes: a. present b. proposed