# CPM question



## NotYet (Feb 19, 2015)

Correct answer is "D", not "C"??? Why?

Hate exam~


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## matt267 PE (Feb 19, 2015)

I am a Gigantic DoucheBag


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## NotYet (Feb 19, 2015)

I know~ Here is attachment...

How to delete post anyway?


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## matt267 PE (Feb 19, 2015)

An admin or moderator can delete the post.

Do you know why the answer is d? I'll have to check my notes.


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## ptatohed (Feb 19, 2015)

They're not asking for the critical path. They are asking for the minimum time to complete the project. Look at the diagram from a common sense point of view. The minimum time that has to go by before Task D can start is limited by Activity 7, right? 30 days. Even if Activities 1, 2, and 3 can be done in 25 days, doesn't matter. The project can't go on until Activity 7 is complete. 30 days. Then Activities 4 and 5 will take 20 days. 30 + 10 + 10 = 50. The project can't go from start to finish any sooner than 50 days.


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## The Wizard (Feb 19, 2015)

ptatohed said:


> They're not asking for the critical path. They are asking for the minimum time to complete the project. Look at the diagram from a common sense point of view. The minimum time that has to go by before Task D can start is limited by Activity 7, right? 30 days. Even if Activities 1, 2, and 3 can be done in 25 days, doesn't matter. The project can't go on until Activity 7 is complete. 30 days. Then Activities 4 and 5 will take 20 days. 30 + 10 + 10 = 50. The project can't go from start to finish any sooner than 50 days.


Actually, they are asking for the critical path. Critical path is the longest path through the network, which corresponds to the minimum time to complete the project. D is the answer.


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## ptatohed (Feb 19, 2015)

The Wizard said:


> ptatohed said:
> 
> 
> > They're not asking for the critical path. They are asking for the minimum time to complete the project. Look at the diagram from a common sense point of view. The minimum time that has to go by before Task D can start is limited by Activity 7, right? 30 days. Even if Activities 1, 2, and 3 can be done in 25 days, doesn't matter. The project can't go on until Activity 7 is complete. 30 days. Then Activities 4 and 5 will take 20 days. 30 + 10 + 10 = 50. The project can't go from start to finish any sooner than 50 days.
> ...




Thanks Wiz. I thought the critical path is 40, no?  15 + 5 + 10 + 10 = 40.


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## matt267 PE (Feb 20, 2015)

The Wizard said:


> ptatohed said:
> 
> 
> > They're not asking for the critical path. They are asking for the minimum time to complete the project. Look at the diagram from a common sense point of view. The minimum time that has to go by before Task D can start is limited by Activity 7, right? 30 days. Even if Activities 1, 2, and 3 can be done in 25 days, doesn't matter. The project can't go on until Activity 7 is complete. 30 days. Then Activities 4 and 5 will take 20 days. 30 + 10 + 10 = 50. The project can't go from start to finish any sooner than 50 days.
> ...


I agree


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## John QPE (Feb 20, 2015)

This problem is really easy, it is asking for the "minimum' time to complete the building, so you are actually looking for the "longest" path.

7 &gt; 4 &gt; 5 = 50 days


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## ptatohed (Feb 20, 2015)

John Q said:


> This problem is really easy, it is asking for the "minimum' time to complete the building, so you are actually looking for the "longest" path.
> 
> 7 &gt; 4 &gt; 5 = 50 days




But wouldn't the longest path be 35 + 10 = 55?


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## matt267 PE (Feb 20, 2015)

ptatohed said:


> John Q said:
> 
> 
> > This problem is really easy, it is asking for the "minimum' time to complete the building, so you are actually looking for the "longest" path.
> ...


35+10=45


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## Supe (Feb 20, 2015)

*Don't let the arrows mislead you. They don't point to where the cumulative dates are.*

Up to point "D", the order and delivery of the metal building is your limiting factor. That takes 30 days, whereas excavation, reinforcing steel, footings, slab, and electrical can be accomplished in 25 days.

From point "D" to point "E", building erection is your limiting factor. That's because the building erection takes at least 10 days to complete following "D", which we determined took at least 30 days. So, 30+10 = 40, which is greater than the 35 days it takes to receive your misc. hardware.

Since installation takes 10 days beyond "E", 40+10=50 days minimum.

Of course, this is just a regurgitation of what has been stated above.


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## IlPadrino (Feb 21, 2015)

> *Activity on Arc (AoA)*
> 
> AoA (also known as Activity on Branch) has the activity represent by the arrows themselves and the nodes represent the precedence as points in time where predecessors have been completed. There are three simple rules to creating the AoA precedence diagram:
> 
> ...




This would count as a "simple" AoA diagram.


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