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 under control with regard to a particular quality variable. Accordingly, he sampled four units of output from each machine, with the following results: $$\begin{array} {r } { \text { Measurements } } \\\begin{array} { l l l l l } \text { Machine } & \\\hline \# 1 & 17 & 15 & 15 & 17 \\\# 2 & 16 & 25 & 18 & 25 \\\# 3 & 23 & 24 & 23 & 22\end{array}\end{array}$$ What is the estimate of the process mean for whenever it is under control?

A) 16
B) 19
C) 20
D) 21
E) 23