Twentyfive samples of 100 items each were inspected when a p

Twenty-five samples of 100 items each were inspected when a process was considered to be operating satisfactorily. In the 25 samples, a total of 135 items were found to be defective.

What is an estimate of the proportion defective when the process is in control (to 3 decimals)?
  

What is the standard error of the proportion if samples of size 100 will be used for statistical process control (to 4 decimals)?
  

Compute the upper control limit and lower control limit for the control chart (to 4 decimals, if necessary)?

Solution