Table 5.11
Factors for Calculating Three-Sigma Limits for the $ \bar{x} $
Chart and R-Chart

Source: 1950 ASTM Manual on Quality Control of Materials, copyright American Society for Testing Materials. Reprinted with permission.
-Thermostats are subjected to rigorous testing before they are shipped to air conditioning technicians around the world. Results from the last five samples are shown in the table. Create control charts that will fully monitor the process and indicate the result of X-bar and R-chart analysis.
A) x bar and r chart are both out of control
B) x bar chart is in control but r chart is out of control
C) x bar chart is out of control but r chart is in control
D) x bar and r chart are both in control

Question

Table 5.11
Factors for Calculating Three-Sigma Limits for the $ \bar{x} $ 
 Chart and R-Chart
  
Source: 1950 ASTM Manual on Quality Control of Materials, copyright American Society for Testing Materials. Reprinted with permission.
-Thermostats are subjected to rigorous testing before they are shipped to air conditioning technicians around the world. Results from the last five samples are shown in the table. Create control charts that will fully monitor the process and indicate the result of X-bar and R-chart analysis. 
A) x bar and r chart are both out of control 
B) x bar chart is in control but r chart is out of control 
C) x bar chart is out of control but r chart is in control 
D) x bar and r chart are both in control

Quizplus · Accepted Answer

To determine if the X-bar and R charts are in control, we need to calculate the mean and range of each sample, calculate the control limits, and plot the data. Using these calculations, we can see that both the X-bar and R charts are within the control limits, indicating that the process is stable and under control. Therefore, the best choice is D, where both charts are in control.

Table 511 Factors for Calculating Three-Sigma Limits for The The xˉ \bar{x} xˉ

Table 511
Factors for Calculating Three-Sigma Limits for The The $\bar{x}$