solution

Problem 17502:
Do not include anything other than numbers in your responses. For example, do not include comma or dollar sign in your numbers. As a rule of thumb, keep 2 decimal places for larger numbers and 3 decimal places for smaller numbers less than 1.
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.
Time for the glue to dry:

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):
D4: