Problem:
Suppose that you have calculated the control limits for a p-chart to be: LCL = 0 and UCL = 0.1. Today you took 10 samples of 15 units each. The first nine samples each had no defect. The last sample had three defects.
Question 1) What can you conclude?
i) The proportion of defect for sample 10 is 0.3, therefore the process is still in control.
ii) The proportion of defect for sample 10 is 0.05, therefore the process is still in control.
iii) The proportion of defect for sample 10 is 0.2, therefore the process is out of control.
iv) The proportion of defect for sample 10 is 0.3, therefore the process is out of control.
A new UCL and LCL should be computed.
Explain the solution in detail.