Return to problem 4 relating to Aspen Plastics producing plastic bottles to customer order. Suppose that the specification for the bottleneck diameter is 0.600 
0.050 and the population standard deviation is 0.013 inch.
a. What is the Process Capability Index?
b. What is the Process Capability Ratio?
c. If the firm is seeking four-sigma performance, is the process capable of producing the bottle?
Problem 4
Aspen Plastics produces plastic bottles to customer order. The quality inspector randomly selects four bottles from the bottle machine and measures the outside diameter of the bottle neck, a critical quality dimension that determines whether the bottle cap will fit properly. The dimensions (inch) from the last six samples are
Assume that only these six samples are sufficient, and use the data to determine control limits for an 
– and an 
-chart.
