A variety of packaging solutions exist for products that must be kept within a specific temperature range. Cold chain distribution is particularly useful in the food and pharmaceutical industries. A packaging company strives to maintain a constant temperature for its packages. It is believed that the temperature of its packages follows a normal distribution with a mean of 5 degrees Celsius and a standard deviation of 0.3 degree  Celsius. Inspectors take weekly samples for 5 weeks of eight randomly selected boxes and report the temperatures in degrees Celsius. A portion of the data is given below.

a. Construct an x̅ chart for quality control. Plot the five weekly sample means on the x̅ chart.

b. Are any points outside the control limits? Does it appear that the process is in control? Explain.

Transcribed Image Text:

Week 1 Week 2 Week 3 Week 4 Week 5 3.98 3.98 5.52 5.79 5.14 5.52 6.42 4.99 5.79 6.25 4.95 4.28 5.95 4.95 5.44