Control Chart question

Submitted by pmasp1 on Tue, 11/29/2011 - 04:54

Can you please let me know the answer for this question:

Question 43: You are producing aluminum dowels. The control limits of this
production process are 14.9cm and 15.1cm. The specification limits are 14.8cm and
15.2cm. Inspection shows that the last 5 dowels produced are 15.2cm long. What do
you do?
A.) Deliver them to the customer.
B.) Don’t’ deliver them to the customer.
C.) The process is out of control and needs to be adjusted.
D.) You should not be inspecting because you have clear control and specification
limits.

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krantikumar50

Tue, 11/29/2011 - 05:34

Ideally when seven consecutive numbers are up or below the spec limit then it should be investigated. The questions does not specify if the work is over and if yes then it can be delivered to the customer else it should be adjusted upon little more investigation.


 


As per the usual PMP style, again two options seems to be correct A and C.


 


Maybe experts can testify more on it.

kmrk

Tue, 11/29/2011 - 06:07

As per the control chart, a process is considered to be out of control when a data point exceeds its control limt or if 7 consecutive points are above are below the mean. According to this definition 15.2 is with-in thee control limits and I would go with "A".

krantikumar50

Tue, 11/29/2011 - 07:34

As per the question, during inspection the above-mentioned observation comes into play. So, the project is over almost. Therefore, I would also go with "A".

pmasp1

Wed, 11/30/2011 - 22:25

Control limit is 14.9 and 15.1 and 15.2 is not within control limit ..So how the answer A is correct ?

 

BTW the correct Answer is A.

pmasp1

Wed, 11/30/2011 - 22:47

I meant correct answer as per the test is A nut i am not convinced with reason ?

dalrsmith

Thu, 12/01/2011 - 01:47

 They're still in the specification limits.  

pmasp1

Thu, 12/01/2011 - 15:07

But as per PMBOK guide ... Admin please answer this question

As per the control chart, a process is considered to be out of control when a data point exceeds its control limt or if 7 consecutive points are above are below the mean...

I am not sure QC consider the specification limit ?

dalrsmith

Sat, 12/03/2011 - 18:13

There are a variety of factors that could signal out of control, not just 7 consecutive points above/below the mean.


 


I wonder if these will be taken into account for the test?  I have a book on lean processes and it has a ton of these little things pertaining to where the data points are or should be.

bunnynbear's picture

bunnynbear

Fri, 01/06/2012 - 21:32

Specification Limits: while control limits represent the performing organisations standards for quality, the specification limits represents the customers expectations or contractual requirements. To meet customers specification limits, the performing orgs control limits must be stricter than those of the customer. Therefore, on the exam, assume that specification limits are outside the upper and lower control limits.


So A : Deliver them to the customer is correct