Activity duration

Hello, I have a question about activity duration. I'm studying in Rita's book. Here the activity duration is assumed EF-ES or LF-EF. In some Internet exercises I find a different calculation: EF-LF+1. Which is the right one? Why there is this difference? Thanks

My guess is, you are getting

My guess is, you are getting confused between formula for calculating float and fomula for calculating activity duration. I am saying so because, LF-EF (mentioned in your question) is a formula to calculate Float of an activity and not the duration of it.

Fomula for calculating activity duration is EF-ES+1 or LF-LS+1.

For example:-

• EF=5th Day
• ES=2nd Day

So, effectively your team will be working for 4 days (2nd, 3rd, 4th and 5th) and not 3 days.

• EF-ES= 5-2 = 3 days
• EF-ES+1= 5-2+1 = 4 days

Regards,

Hemant, PMP

Thank you for

Thank you for explanation.Your approach is different from Rita's chart: this is the reason of my confusion. I think that the difference is because Rita start from 0, not from 1, in the critical path calculation. ex activita A (with duration 4) start at 0 and end at 4. So the  duration is EF-ES=4-0.

Other exercises in other books use the formula EF-ES+1. My doubt is: wich is the correct approach for PMP exam?

Thanks

refer blog dated

refer blog dated  26th of Dec 12

on

er-sspawar.blogspot.in