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 findustries. 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=degrees Celsius and a standard deviation of 0.3 degree Celsius. Inspectors take weekly samples for=weeks of eight randomly selected boxes and report the following temperatures in degrees Celsius. A portion of the data is given below; the complete data, labeled Packaging , are available on the text website.

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

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