# 3 point estimates

Submitted by vivek919 on Fri, 04/12/2013 - 02:41

A project manager made 3-point estimates on a critical path and found the following results: Assuming ±3 sigma precision level for each estimate, what is the standard deviation of the allover path? |
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App. 4.2 days | ||

App. 5.2 days | ||

App. 6.2 days | ||

You can not derive the path standard deviation from the information given. |

Can you pleaseexplain how?

Forums:

sspawar

Fri, 04/12/2013 - 05:58

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## see old posts

see old posts

Hemant Tandon

Sat, 04/13/2013 - 23:42

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## Answer to your question

Some points to remember:-o

V=(SD)

^{2}Apply above mentioned points for calculating the SD of allover path. Calculate SD of individual task:-

Calculate V of individual task:-

^{2 }=^{ }4Calculate V of allover path:-

Calculate SD of allover path:-

Let me know if you still have any confusion.

Thanks & Regards,Hemant Tandon, PMP, CAPMphilzs

Wed, 01/14/2015 - 14:22

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## The question ask the Standard

The question ask the Standard Deviation and we calculate the Sum of the Variation and we Square it,

I dont understand why we talk about Standard deviation and play with Variation as it's two different thing

kniraj

Mon, 01/19/2015 - 11:18

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## Philzs,

Philzs,

The standard deviation of the entire path is the square root of the variance of individual activity as rightly mentioned by Hemant.

This is different from the standard deviation of an individual activitiy.

philzs

Sun, 01/25/2015 - 18:16

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## thanks

thanks