The product we make is a type of glue. We are advertising that our glue dries very fast. To monitor the quality of the produced glue, we record the time it takes for the glue to dry for each batch of glue we make. The following table summarizes the data we collected during the last 4 days. In each day, we produced 3 batches of glue and recorded the time of each batch. All values are in minutes. We know the standard deviation of the process is approximately 0.15 minutes.

Required:

Calculate the center line to control the average of the time it takes for the glue to dry.

Calculate the average of ranges to control the variability of the time it takes for the glue to dry.

Number of observation in each sample (n)

Upper Control Limit to control average of the time it takes for the glue to dry

Lower Control Limit to control average of the time it takes for the glue to dry

Is the average of the process in control? Yes No

Upper Control Limit to control variability of the time it takes for the glue to dry

Lower Control Limit to control variability of the time it takes for the glue to dry

Is the variability of the process in control? Yes or No

Sample-1 Sample-2 Sample-3 Sample-4 Obs-1 Obs-2 Obs-3 6.95 6.93 7.24 7.36 7.54 7.13 7.9 7.7 7.63 7.01 7.58 7.67