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TOPIC: Why is this the correct answer?

Why is this the correct answer? 2 years 3 months ago #4589

  • SANDHYARANI P BHIDE
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Hi,

I don't understand how this answer was calculated for the question from Oliver Lehmann's free 75 question test.
Can anyone please enlighten? The correct answer is B ie. approx. 5.2 days.

27. A project manager made 3-point estimates on a critical path and found the following results: (Check attached table below)

Assuming ±3 sigma precision level for each estimate, what is the standard deviation of the allover path?

(A) App. 4.2 days
(B) App. 5.2 days
(C) App. 6.2 days
(D) You can not derive the path standard deviation from the information given.
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Why is this the correct answer? 2 years 3 weeks ago #4774

  • Ivan Fućak
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You can use following link for calculation:
www.firebrandtraining.co.uk/learn/pmp/co...e-activity-durations
You have to calculate standard deviation for each activity.
(24-12)/6=2,
(14-8)/6=1,
(27-15)/6=2,
28-10)/6=3,
(35-17)/6=3
Variances of each activities are squares of deviations of activities.
Stand.deviation of path is square root of sum of variances:
SQRT(4+1+4+9+9)=SQRT(27)=5,19

Why is this the correct answer? 4 months 3 weeks ago #7772

  • Mohammed Yaseen
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For +_ 3 Sigme, the standard deviation = 3 * Standard Deviation of 1 Sigma prceision level.

So in this case, the standard deviation should be = 3 * 5.19 = 15.57

Hope, I am right.
If not, PLEASE explain me.

Why is this the correct answer? 3 weeks 9 hours ago #8918

  • shravan
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Waw...Super..I got it...thanks a lot...dint understand logit behind t ...but doesnt matter

Why is this the correct answer? 2 weeks 6 days ago #8926

  • Hazem Ibrahim
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please note that putting ±3 sigma precision level in the question is meaningless and useless it is just to scatter you away
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