Which scenario does the calculation of SD with square-root and sqaure?

PMP Fighter's picture

I have did one question few month ago is calculate the SD from PERT estimate (P,M,O).

But we know the SD formula is (P-O)/6

So can anyone recommend some question example about SD with square-root calculation ?

Hi PMP Fighter

I have done a similar question but it was a while ago
I remember it was for finding the standard deviation for a series.When you have a list of activities and need to find the SD for the entire series,you cannot add the individual values.Instead you have to add all the individual variances and find its square root to give the SD of the series.

Variance = SD*SD

Anyone please confirm.Im not completely sure of the answer.

BTW have you scheduled your exam?
I have my exam closely approaching.Maybe we could share some common strategies

"Unity is Strength"


Feel free to contact me at binaas@gmail.com

PMP Fighter's picture

Ya, you trigger my memorize, i remember i do this is about sum the SD from individual values, i try to Google find the question, but no lack.

I scheduled my exam on 19/Jun, actually i do

Whizlabs Exam 800Q
Rita Fast track PMP 4 times x 200Q
PM HeadFirst 200Q
Simplilearn 200Q

My result is about 66 - 70%, so i am not confident to pass the real exam.
I just make a bet on it.

I live in Hong Kong and my parent language is traditional Chinese,
so i am easy to get into trap of tricky question :(

It is 10 day left,
I keep doing mock exam on excremental and pmp4sure, and i have to spend 3 days to read though rita exam prep once time.