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# D1 (Decision 1) 17 May 2013 Official Thread Watch

1. (Original post by Vaner)
Do you suggest doing solomon now? Also just to clarify, I can do diagrams in pen or pencil?

Thank you!
Arsey recommends a nice dark pencil for all of D1
2. (Original post by Anythingoo1)
Ok thanks alot! Also just to be sure, say the objective line was P = 5x + 7y, and your graph went up in all the way to 60 on both axes, would it be ok to double it (x = 14, y = 10) ?

definitely, they will not accept an objective line if it is too small. It needs to be big enough to follow the gradient through.
3. (Original post by Arsey)
Arsey recommends a nice dark pencil for all of D1
Mind is blown lol. Can we seriously answer in Pencil?
4. (Original post by Arsey)
I agree with you to a certain extent. The Solomon ones are based on old spec, so I went through them and binned all flows and simplex and currect spec questions that were just stupidly hard.

Most of the Solomon questions are fine and help prepare you for the awkward Edexcel questions.
Sir if you were to guess what definitions/explanations would we get in this exam??

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5. (Original post by Better)
Things just got serious. Arsey is here.

Arsey is there a faster way to do Linear Programming Vertex Testing. I just did January 2013 and I finished on time but the Vertex Testing took me a very long time.

Any help would be appreciated.

Ruler method all the way. I only ever paid lip service to ruler method with my students... until Jan... I let out a few expletives when I saw the YOU MUST USE POINT TESTING... 3-4 marks down the pan for most of mine.
6. (Original post by Arsey)
technically no, but on one of the past papers they accepted solutions on the dotted line in the answers.

2. flows is unlikely to be on as the sorting algorithms have to be on but it doesn't matter.
Sir do you think for route inspection they could either ask us on if you add this route the length would increase or decrease, or could another option be if G starts here which point will it finish?

Are these 2 the things we always get for route inspection
7. (Original post by Flounder1)
Sir if you were to guess what definitions/explanations would we get in this exam??

Posted from TSR Mobile

Tree etc or matchings

I think I uploaded my definitions you need to know sheet on the other thread.
8. Hey guys hope revision is going good! I have a question thats confused me a little on the D1 May 2011 paper. Question 4 about matchings
a) I got A-1 = H-2 and A-1=H-3=C-5 the second one is not on the ms so is it incorrect?
likewise part c) I got J-4=C-3=H-2, which is also not on the ms?
Any help is appreciated!
9. (Original post by posthumus)
Aaaahhhh damn it ! But what do they mean by "correct order"

& Thanks for the response !
As soon as you put a final label on a vertex, you put a working value on every vertex that is directly connected to it except the ones which already have final values. Have a look at the steps for Dijkstra's algorithm again if you still don't understand.
10. (Original post by Vaner)
Mind is blown lol. Can we seriously answer in Pencil?
Of course you can. They prefer black pen because it shows up clearer on their scanners but you can write in luminous pink if you wish, they have to mark it regardless...

that said, it probably isn't wise to annoy a marker. Don't draw them little pictures or write them messages, rarely goes down well.
11. (Original post by Arsey)
definitely, they will not accept an objective line if it is too small. It needs to be big enough to follow the gradient through.
Sweet, thanks a bunch, this was the only thing I wasn't sure about up till now and you've explained it brilliantly.

I know there's people here who probably need you more than I do but just quickly which definitions do you think catch people out more, if that even makes sense?

Btw I sent a +rep your way, a lifesaver the way you help on this thread
12. (Original post by Arsey)
Tree etc or matchings

I think I uploaded my definitions you need to know sheet on the other thread.
Final Question Arsey, please would you be able to join the C3/C4 Forum and give some wisdom to us wanting to get A*s after the D1 Exam.

The general consensus on the forum has been Solomon Press ---> Real papers will get you to a 100UMS Level but some professional guidance would be great. TinyHobit (also a teacher said she might pop on when she has time).

13. How do you find the optimal solution using the ruler method if it has to be in integars???????
14. (Original post by Arsey)
" "
Thank you so much !

(Original post by Pebbles94)
As soon as you put a final label on a vertex, you put a working value on every vertex that is directly connected to it except the ones which already have final values. Have a look at the steps for Dijkstra's algorithm again if you still don't understand.
Oh okay, I get it now... thanks ! I just haven't had any practice doing so, so now I'm starting to get worried
15. Hello there,
I have a question about a paper I have done previously.

It was the Jan 2010 paper, question 5a on algorithms. I set my answer out differently from the mark schemes and still gave myself full marks.

What I suppose I am asking is when you have an algorithm question and you need to fill in a table, does it matter how you put the values into the table? I tend to write across filling in the boxes across as I go along, but the mark scheme seems to start a line for every box.

Which is the right way?

Many thanks

Toby
16. (Original post by Story)
Hey guys hope revision is going good! I have a question thats confused me a little on the D1 May 2011 paper. Question 4 about matchings
a) I got A-1 = H-2 and A-1=H-3=C-5 the second one is not on the ms so is it incorrect?
likewise part c) I got J-4=C-3=H-2, which is also not on the ms?
Any help is appreciated!
Part a) You've wrote 3=C in your second one, 3 isn't matched to C, it's matched to R

so it would be A-1=H-3=R-4=C-5
17. Does anyone know whether we will need to be able to draw the activity network?
18. (Original post by Westeros)
Part a) You've wrote 3=C in your second one, 3 isn't matched to C, it's matched to R

so it would be A-1=H-3=R-4=C-5
thanks for the quick reply im still a little confused though, so part a is wrong?
19. (Original post by Nitrogen)
Does anyone know whether we will need to be able to draw the activity network?
Fairly possible I would say Though I would imagine it must be a pain for the examiner to mark ! Since students will get a variety of funky shapes
20. I am doing the may 2008 paper and it has some odd questions... can someone tell me if there part of the specification or not...? Like this one....

..

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