I purchased the IASSC Black Belt Evaluation Exam one question in the set said :
From this control chart with a center line indicated by line number 4, which of the following observation numbers is more than 2 sigma from the mean?
the proposed answers are :
A) 5
B)9
C) 13
D) 15
E)17
F)23
trying to synthesize the elements to answer the questions, it seems to me that something is missing.
Finally I sent an email to IASS They answered me that the question is fair and complete.
Now I find the basis for answering the question.
Any ideas?
thank you
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