A computer manufacturer uses three suppliers of printed wiring boards (PWBs). Electronic components are hand or machine inserted and clinched in the PWBs by the computer manufacturer to form printed wiring assemblies (PWAs) that are processed through an automatic wave soldering machine. The computer manufacturer is concerned that the quality of the PWBs may differ among the suppliers. Information was collected on PWBs from each supplier in the following manner - five PWBs from each supplier received electronic components from the same lots and received wave soldering treatment at the same time. This was repeated for five time periods at two-hour intervals. Determinations as to the number of solder defects were made for each PWA. All inspections were performed by the same inspector. Results for this study can be found in the Minitab worksheet PWA.MTW.
Which of the suppliers provides the highest quality PWBs?