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# Edexcel D1 - 17th June, 2016 [Exam discussion] Watch

1. (Original post by NotNotBatman)
Because once it reaches T, the route has ended, so there's no need to add 2 on to the last arcs of the route. Also, you add 2 to every arc except GT and HT, not only the ones on the shortest route, as you'd have to do it prior to doing dijkstra's algorithm, that's why it's not added to GT and HT and not just one or the other.
Ah I see, thanks so much
2. How do you find the shortest route in Dijkstra's algorithm without going through a particular arc that would be included in the shortest route ? Like in question 6(c):
3. (Original post by NotNotBatman)
How do you find the shortest route in Dijkstra's algorithm without going through a particular arc that would be included in the shortest route ? Like in question 6(c):
I don't think there's any particular method unfortunately, I think you just have to keep trial and erroring to see which route is the shortest :/
4. (Original post by economicss)
I don't think there's any particular method unfortunately, I think you just have to keep trial and erroring to see which route is the shortest :/
Well that's a shame. Thanks for the help.
5. When you draw an precedencd table and the graph, how do you deduce the critical activities?
6. (Original post by Pablo Picasso)
When you draw an precedencd table and the graph, how do you deduce the critical activities?
The float of the activity, calculated by the (late event time at the head - activity duration - early event time at tail), should be equal to 0.
7. Please could anyone explain question 6d here https://d0247e65b1a6ead8e6286cd43803...%20Edexcel.pdf how do you know what objective line equation to use since the objective line I drew didn't lead to the correct answer, thanks
8. Also does anyone know please whether questions like 8d and 8e https://d0247e65b1a6ead8e6286cd43803...%20Edexcel.pdf are in the spec, not seen questions like them before, thanks
9. (Original post by economicss)
Also does anyone know please whether questions like 8d and 8e https://d0247e65b1a6ead8e6286cd43803...%20Edexcel.pdf are in the spec, not seen questions like them before, thanks
The spec changed back in 2009 so any past papers before that may have some stuff not in the spec.However question 8d and 8e look okay to do
10. Is the any difference between the IAL spec and the UK spec?

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11. (Original post by Glavien)
Is the any difference between the IAL spec and the UK spec?

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No.
12. How would you do part (d) question 5 of the January 2006 paper? I would've just guessed through trial and error but there must be a better way right?

The spec changed back in 2009 so any past papers before that may have some stuff not in the spec.However question 8d and 8e look okay to do
Thank you, I understand 8d now but how would you find the total time needed to complete the project please, as we don't have any early or late event times? Thanks
14. (Original post by economicss)
Please could anyone explain question 6d here https://d0247e65b1a6ead8e6286cd43803...%20Edexcel.pdf how do you know what objective line equation to use since the objective line I drew didn't lead to the correct answer, thanks
Please could anyone help with this one? Really struggling with it, thanks!
15. What the?!

Can someone please confirm that Ex 5A question 4 (Chapter 5 - Critical Path Analysis) shows the same activity network in their D1 edexcel textbook as is on the solutionbank here?
https://86495a24d9b181f09087f4168bce...VJZTW8/CH5.pdf
My textbook has a completely different arrangement of letters I,K,J and L.

Thanks!
16. (Original post by tripleseven)
What the?!

Can someone please confirm that Ex 5A question 4 (Chapter 5 - Critical Path Analysis) shows the same activity network in their D1 edexcel textbook as is on the solutionbank here?
https://86495a24d9b181f09087f4168bce...VJZTW8/CH5.pdf
My textbook has a completely different arrangement of letters I,K,J and L.

Thanks!
Yeah, it's different in the textbook and the answers at the back is wrong, J depends on G, not H.
17. For question 2(a) of the June 2010 paper, why did they reject arc BD?

18. (Original post by Glavien)
For question 2(a) of the June 2010 paper, why did they reject arc BD?

They didn't, it's just written under CE, to show that it has the same weight, so it doesn't matter what order it's written in, 'NOT CE' is just referring to the arc CE, but BE is added.
19. (Original post by NotNotBatman)
They didn't, it's just written under CE, to show that it has the same weight, so it doesn't matter what order it's written in, 'NOT CE' is just referring to the arc CE, but BE is added.
Ohhh, thanks for that.
20. (Original post by Glavien)
How would you do part (d) question 5 of the January 2006 paper? I would've just guessed through trial and error but there must be a better way right?

The tagging system isn't working properly for me.

For this question you would just have to look at the area of the Gantt chart with the most overlaps. If I were doing this question, I would look around the place where there's a lot of activities occurring with minimal floats, as there's not a lot of room for manoeuvre and then consider an interval of time, where activities must be taking place.

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