Question

A quality analyst wants to construct a control chart for determining whether four machines, all producing the same product, are under control with regard to a particular quality attribute. Accordingly, she inspected 1,000 units of output from each machine in random samples, with the following results:



For upper and lower control limits of .026 and .014, which machine(s), if any, appear(s) to be out-of-control for process proportion of defectives?

A. machine #3

B. machine #4

C. machines #3 and #4

D. machines #2 and #3

E. none of the machines

Answer

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