Sampling Plan Questions from the CQE Practice Exam

[JeantheBigone]

Could someone with experience using the ANSI/ASQ Z1.4 sampling plan tables help me? I'm studying for the ASQ CQE and have been taking practice exams. I suspect that sometimes the practice questions may be flawed; either that or I am missing something.

It seems to me that the correct answers to the following two questions are contradictory.

1. A lot size of 2000 is to be inspected using ANSI/ASQ Z1.4-2003, with an AQL of 0.15 %. Use a single normal level II plan. The correct sample size is:

A) 20
B) 40
C) 60
D) 80
E) none of the above.

I get code letter K, which has sample size of 125. For AQL=0.15%, this corresponds to a location in Table II-A with an upward arrow. The "correct" answer is D) 80, because the arrow upward points to sample size 80, Ac=0, Re=1. So the arrow determines sample size, Ac and Re.

A similar question is this one:


2. A lot size of 500 is to be inspected using ANSI/ASQ Z1.4-2003, with an AQL of 0.65 %. Use a single normal level II plan. What are the correct sample size, acceptance number and rejection number?:

A) n=50, Ac=0, Re=1
B) n=50, Ac=1, Re=2
C) n=80, Ac=0, Re=1
D) n=80, Ac=1, Re=2


I get code letter H, which has sample size of 50. For AQL=0.65%, this corresponds to a location in Table II-A with a downward arrow. The "correct" answer is B) 50/1/2, because the arrow downward points to sample size Ac=1, Re=2, but the sample size seems to be determined by Code letter only.

What I don't understand is that the correct answer to the 1st question has the arrow in the table determining sample size, Ac and Re, while the correct answer to the 2nd question appears to have the sample size determined by code letter only, but Ac and Re depend on arrows (if any).

Is there something about whether sample sizes can increase or decrease, or is there possibly a mistake in the practice questions?

 

[David-D]

Re: Sampling Plan questions from CQE practice exam

I looked at MIL-STD-105 (readily available) and I would say they provided you the wrong answer for the 2nd question. The arrow should have you change both the sample size and the accept-reject criteria. For the first question you should get 80(0-1) and the second should be 80(1-2). Unfortunately I have found over the years that the quality of the prep materials are often not as good as the questions on the ASQ exams themselves.

Best of luck on the exam,

David

 

[Statistical Steven]

Re: Sampling Plan questions from CQE practice exam

The "correct" answer is wrong. The answer should be "D". Possible it was caught as incorrect, removed from active test bank and used as a practice exam question without the answer being fixed.