On the course notes it says that using the Six Sigma approach you must ensure that rejection rates are below 3.4/million. However, when working a question from June 2012 (Thebe) the answer shows that rejection rates must be below 6/million. Which is correct please?
3.4/million is correct. I think the answer to The be misunderstood what the ‘6’ stands for. It means rejection rate is beyond 6 standard deviations from the mean.