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D1 (Decision 1) 17 May 2013 Official Thread Watch

1. (Original post by otrivine)
No you sometimes they want you to find the number of minimum workers needed , sometime they say use your gantt chart to do that but sometimes even if u want to use the lower bound it does not give u the same number of workers sometimes when u use the gantt you need 4 workers and in lower bound you get 3 why the difference
right i've used my d1 lessons to catch up on sleep, can someone explain to me the difference between the lower bound and the minumum number of workers? and how do you work each one out?
2. (Original post by otrivine)
No you sometimes they want you to find the number of minimum workers needed , sometime they say use your gantt chart to do that but sometimes even if u want to use the lower bound it does not give u the same number of workers sometimes when u use the gantt you need 4 workers and in lower bound you get 3 why the difference
Oh okay that's kind of hard then if they tell you to use a gantt chart to find the minimum number of workers required I guess you'll just have to imagine.

yup the whole idea of lower bound is to give you the lowest possible, or theoretically the minimum amount of workers you would need. Sometimes this wouldn't be so practical
3. I'm going to lose so many marks if I don't sort out my notation.
4. What is coming up for sure? IMO bubble sort must come up and drawing the CPA
5. D1 Notes ( Every bit in your book in the notes :O ! )
Attached Files
6. D1 (1).pptx (244.5 KB, 431 views)
7. (Original post by QwertyG)
What is coming up for sure? IMO bubble sort must come up and drawing the CPA
We can't say for sure obviously, but Arsey made these following predictions earlier :

(Original post by Arsey)
Okay guessing time. Here is what I expect to come up in the exam tomorrow.

Definitions - they love the reason for a dummy definition but I would expect definition on algorithms on networks or matchings.

Kruskal's, that is pretty certain to come up. Make sure you know the differences between Prim's and Kruskal's.

Sorting algorithm, you will either get Bubble or Quick, probably numerical descending order, which is likely to lead into...

Bin Packing - Make sure you know how to find the lower bound / proving a solution is maximal.

CPA - Maybe drawing an activity network and my money would be on a Gantt. Make sure you know how to find a lower bound from the activity network AND from a Gantt.

Linear Programming - Hammer linear programming, it is on every paper and is often the poorest answered. Unless you know how to go from context to a restriction you could be absolutely stuffed. Also make sure you know the basics, y = mx + c, if you don't know how to draw a line, do a table of values! you only need 3 points. I wouldn't be surprised if you get a decimal point but require an integer solution, so practise these.
(Original post by IWantSomeMushu)
I'm going to lose so many marks if I don't sort out my notation.
I fear this too Though I've improved a lot since January !!
8. I hope we don't have to draw an activity network!

When you're doing Dijkstra's algorithm and you have, let's say, point G with a working value of 15. Then the second working value you do is bigger than 15, do you still write it in and cross it out? Or do you just leave it out completely?!

Thank you! x
10. (Original post by niki135)

When you're doing Dijkstra's algorithm and you have, let's say, point G with a working value of 15. Then the second working value you do is bigger than 15, do you still write it in and cross it out? Or do you just leave it out completely?!

Thank you! x
If it is bigger then don't write it in at all.
11. Since IWantSomeMushu has brought it up, does anyone know what on earth is going on with the numbering of nodes in activity networks? Are we marked on how we have numbered our nodes, or is that just for personal reference.

Also what is the procedure, do I label them in ascending order as I plot the network I hope it's not compulsory
12. (Original post by posthumus)
Since IWantSomeMushu has brought it up, does anyone know what on earth is going on with the numbering of nodes in activity networks? Are we marked on how we have numbered our nodes, or is that just for personal reference.

Also what is the procedure, do I label them in ascending order as I plot the network I hope it's not compulsory
I think they do care about the numbering of the nodes, you start with 0 and move along, such as then put 1 an 2 does not matter which way you put it
13. (Original post by niki135)

When you're doing Dijkstra's algorithm and you have, let's say, point G with a working value of 15. Then the second working value you do is bigger than 15, do you still write it in and cross it out? Or do you just leave it out completely?!

Thank you! x
I crossed it out to show the examiner that I am choosing the smaller value but very weirdly in the mark scheme they leave it, I would suggest you not to show any cancelling to be on the safe side
14. (Original post by IWantSomeMushu)
If it is bigger then don't write it in at all.
My teacher tells me that you should always write every working value you obtain - even if it is bigger than your lowest working value, just put it in brackets... .

Imagine you get 26 then 23 then 24, you would write 26 [space] 23 [space] then (24) - note the brackets... .

Don't give them an excuse to take a mark off you!!
15. (Original post by tobywalsh)
My teacher tells me that you should always write every working value you obtain - even if it is bigger than your lowest working value, just put it in brackets... .

Imagine you get 26 then 23 then 24, you would write 26 [space] 23 [space] then (24) - note the brackets... .

Don't give them an excuse to take a mark off you!!
if its bigger i usually show a cross that this is not the smallest
16. Out of curiosity, I hope it doesn't come up bearing in mind, what do you do if you get two critical activities occurring at the same time? For a Gantt chart do you just draw them on different lines?

Thanks!

Toby
17. (Original post by tobywalsh)
Out of curiosity, I hope it doesn't come up bearing in mind, what do you do if you get two critical activities occurring at the same time? For a Gantt chart do you just draw them on different lines?

Thanks!

Toby
Yes you draw it underneath the critical activities
18. (Original post by otrivine)
Yes you draw it underneath the critical activities
Thank you! And also, you're right about the cross for the larger working values, I have done that before in a mock and it worked out! As long as you make it stand out I doubt it'll be a problem including it... .

Toby
19. a quick question
http://www.edexcel.com/migrationdocu...c_20120214.pdf

on the diagram of the gantt chart,

if you were asked which activties must be happening at day 7 would you say C? and if they say which activties maybe happening at day 7 do you say F?
20. (Original post by tobywalsh)
Thank you! And also, you're right about the cross for the larger working values, I have done that before in a mock and it worked out! As long as you make it stand out I doubt it'll be a problem including it... .

Toby
No worries

a quick question
http://www.edexcel.com/migrationdocu...c_20120214.pdf

on the diagram of the gantt chart,

if you were asked which activties must be happening at day 7 would you say C? and if they say which activties maybe happening at day 7 do you say F?
21. (Original post by tobywalsh)
My teacher tells me that you should always write every working value you obtain - even if it is bigger than your lowest working value, just put it in brackets... .

Imagine you get 26 then 23 then 24, you would write 26 [space] 23 [space] then (24) - note the brackets... .

Don't give them an excuse to take a mark off you!!
Huh, I was taught not to put them in.

I'll do it from now on then and put them in brackets.

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