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: $$\begin{array} { c c c c c } \text { Machine } &&{ \text { Measurements } } \\\hline \# 1 & 17 & 15 & 15 & 17 \\\# 2 & 16 & 25 & 18 & 25 \\\# 3 & 23 & 24 & 23 & 22\end{array}$$
For upper and lower control limits of 23.29 and 16.71, which machine(s) , if any, appear(s) to have an out-of-control process mean?

A) machine #1
B) machine #2
C) machine #3
D) all of the machines
E) none of the machines