Quality Control Charts Usually Have a Central Line and Upper

Multiple Choice

Quality control charts usually have a central line and upper and lower control limit lines.Which of the following is not a reason that the process being monitored with the chart should be investigated?

A) A large number of plots are close to the upper or lower control lines.
B) The behaviorbehaviour of the plots is erratic.
C) A single plot falls above or below the control limits.
D) TheeThere is a change in raw materials or operators.
E) There is a run of five above the central line.