Consider a Service Process Such as a Fast Food Drive

Multiple Choice

Consider a service process such as a fast food drive through window. The target for a customer's waiting time is 3.0 minutes. A manager observes the process and randomly collects a sample of four waiting times each hour over a 12 hour period. The sum of the range for each of the 12 samples is 18.0. The UCL for the process control chart reporting variability within the samples is

A) 3.4
B) 4.5
C) 5.6
D) 6.8