## STANDARD DEVIATION

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M L Dahima
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Posts: 157
Joined: Mon Feb 10, 2014 5:13 am

### STANDARD DEVIATION

Following question is from PM Study:
Optimistic Estimate -- 10 days
Pessimistic Estimate -- 16 days
Most likely Estimate -- 13 days
if your company has a quality requirement of Six sigma what is the duration within which task must be completed.

Answer is given 7 days to 19 days.

They considered +/- 6 sigma
whether this is correct ?
My thinking is 6 sigma means +/- 3 sigma
saket
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Joined: Sat Dec 07, 2013 10:37 pm

### Re: STANDARD DEVIATION

You may wana check this out : viewtopic.php?f=11&t=311&p=980
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M L Dahima
Contributor
Posts: 157
Joined: Mon Feb 10, 2014 5:13 am

### Re: STANDARD DEVIATION

OK, Saket
if we go as per (Rita ) +/- 6 sigma, it means 99.9999998 % data above mean and same percentage of data below mean.
But 6 sigma process means 99.999998% data within control limits - between UCL & LCL.
what is the final to follow
harin4627
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Joined: Thu May 29, 2014 6:50 pm

### Re: STANDARD DEVIATION

I think there is a confusion between range of sigma. -/+ 3 sigma gives the range as "6 sigma range" from the upper to lower from the mean. But when it is not mentioning about range, 6 sigma means 3.4 mistakes/deviation out of 1 million.(99.99966% accuracy). So in this question limits becomes +-6 (in terms of range 12 sigma)

am I right?
saket
Posts: 3113
Joined: Sat Dec 07, 2013 10:37 pm

### Re: STANDARD DEVIATION

I go with harin4627, at least for PMP Exam , M L Dahima give the exam now...you are more than ready.
Explore our online PMP Program , it makes PMP Easy http://goo.gl/ZmD3xF