7 writing questions and 5 problem solving

3.1. Explain the difference between attribute control charts and vari- able control charts. _
3.2. How are mean (x-) and range (R-) charts used together?
3.3. What is the purpose of a pattern,test ?
3.4. What determines the width of the control limits in a process chart?
3.5. Under what circumstances should a c-chart be used instead of a p-chart?
3.6. What is the difference between tolerances and control limits?
3.7. Why have companies traditionally used control charts with 3-sigma limits instead of 2-sigma limits?
and 3.3, 3.5, 3.15, 3.27,