A Quality Analyst Wants to Construct a Control Chart for Determining

Multiple Choice

A quality analyst wants to construct a control chart for determining whether three machines, all producing the same product, are in control with regard to a particular quality variable. Accordingly, he sampled four units of output from each machine, with the following results

What is the estimate of the sample average range based upon this limited sample?

A) 13.0
B) 4.33
C) 5.4
D) 4.2
E) 2.0