Consider the relationship between optimal lot size and set-up cost. Other things remaining the same, as the setup cost decreases, optimal production batch size will decrease. optimal production batch size will increase. holding cost will increase. optimal production batch size will stay the same.ich of the following is a reason that the process being monitored with the chart should be investigated? A single point falls above or below the control limits. There is a change in raw materials or operators. A large number of plots are on or near the central line. There is no real trend in any direction. Behavior is normal