A producer of beverage containers wants to ensure that a liquid at 90C will lose no more than 4C after 30 minutes.

Containers are selected at random and subjected to testing. Historical data shows the standard deviation to be 0.2C. The quality control team has set 3.5 and 4.5C as the specification limits. Here are the data from the last 12 containers tested:

Container #
Temperature Loss 1 C2 Container #
Temperature Loss 1 C2 1 3.89 7 4.22 2 3.71 8 4.02 3 4.14 9 4.48 4 4.12 10 3.93 5 3.74 11 3.87 6 3.99 12 3.94

a) Make a control chart of these data using the specification limits given.

b) Does the process seem to be in control?

c) What is the value of Cp for the process?

d) Given this value of Cp, what recommendations might you make to the quality control team?