Arsey's D1 Edexcel Summer 2013 Model Solutions BOTH PAPERS

Just checking the model answers to have a guess at my marks and I can't remember the exact numbers I got for Dijkstra's etc, but I do remember my shortest path for Dijsktra read SADGEHT because I then pictured someone with a strong Scottish accent saying "sad git" and it made me wonder if they'd done it deliberately.

For the difficult inequality I wrote that the number of 2 seaters purchased must exceed the number of 4 seaters purchased by a ratio of 3:2. Although it ties in with the optimal solution I guess I won't get marks for that?

Reply 201

ryanclarke

2

Original post by Jennance

Just checking the model answers to have a guess at my marks and I can't remember the exact numbers I got for Dijkstra's etc, but I do remember my shortest path for Dijsktra read SADGEHT because I then pictured someone with a strong Scottish accent saying "sad git" and it made me wonder if they'd done it deliberately.

I did the same thing. Lost about 5 minutes thinking about it :colondollar:

. Fortunately finished the exam after about 70 minutes so had time to spare. Made some silly mistakes like naming the ED arc as the one to be transversed. I think that was the only mark I lost although I can't remember my exact wording for the 2x<3y thing. Also didn't draw the new matchings so might lose a mark there.

Reply 202

tiny hobbit

15

Original post by jfox2

how many marks would I loose on the dykstras if I got 31 as the answer do you reckon ?

Depends on how soon you went wrong.

Reply 203

jfox2

Original post by tiny hobbit

Depends on how soon you went wrong.

I think just on the last couple of steps..

Reply 204

rber

Hi for the part b question on matching I first found an alternating path and then the change status and then I drew the improved matching. After that I did another alternating path and changed status however I used my improved matching for that, and finally that's how i got my complete matching. Did I do it right if not how much mark would I lose.

Reply 205

Arsey

OP

10

Just finished solutions to the other paper. I think it was a bit harder.

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Reply 206

moko

please i need an answer

hi ARSEY
for the quick sort i multiplied all by 10 to make it easier for me but after sorting i put the final answer back to decimals, would i loose mark for using this method?

for the linear programming i only worked out what x and y is by substituting the equations i did not sub the numbers to find the total cost, how many marks do i loose ?

on question 7 b i only said it would affect the total time because its a critical activity but i didnt say it would be delayed by 2days? would i loose all the marks for this?

for 7f i said at time 12 FDEH would be going on, i know this is wrong but would i get a method mark?

and for 7g I said the chart is better because it shows the activites that needs to be done by the workers.do i have any chance of getting a mark?

THANK YOU

Reply 207

Arsey

OP

10

I have uploaded my solutions to the other time zone paper in the first post.

Reply 208

otrivine

14

Original post by Arsey

Fairly reasonable paper I thought

1. Matchings - pretty simple, although not breaking down the 2 required paths into separate part of the question, could cause problems.

2. Quick sort and Bin packing - very easy, I thought it was odd how the first-fit decreasing didn't reduce the number of bins though

3. Prim's and Kruskal's - very easy

4. Dikky - harder than normal due to the sneaky part of the route. Quite easy to mank up b) too.

5. Postie - standard. A common error on c) will be to repeat DE.

6. LP - not easy but it never is. Part b) will be a bloodbath.

alt to part b)

no more than 1.5 times as many small as large

for every 3 small you need at least 2 big

7. CPA - Fairly standard but the backward scans not using the dummy paths will be a very common error. Gantt chart took too long. f) and g) will be poorly answered.

Overall I would say it was a little easier than Jan, I would expect it to be around 63 for an A.

This summer I will upload solutions to the following Edexcel papers:

Core 1;
Core 2;
Core 3;
Core 4;
FP1;
M1;
M2;
S1;
D1;
D2.

I will try to get hold of some solutions for FP2; FP3 and M3.

I don't do S2 :frown:

All papers will be uploaded in line with site rules (please don't PM me asking when I will I be uploading them).

I have uploaded my solutions to the other time zone paper, which I thought was a bit harder.

OMG, the international paper was much better than ours!

Reply 209

posthumus

20

The international paper looks slightly harder to me, but not by much...

... the activity network & linear programming (especially the points testing) looks quite daunting :tongue:

Reply 210

otrivine

14

Original post by posthumus

The international paper looks slightly harder to me, but not by much...

... the activity network & linear programming (especially the points testing) looks quite daunting :tongue:

Really?! I thought the paper was the same as the specimen papers, looked easier and I loved the 3 mark question on stating the difference of kruskal and prim!

shame :frown:

OP

Scheduling...

Original post by Arsey

Scheduling...

Arsey
For question 7
If I said there would be no effect and there would be an effect but didn't specify days how many marks would I lose?

Reply 213

Azgar

5

For the second time, I couldn't finish this paper in time. :cry2:

Reply 214

rber

Hi for the part b question on matching I first found an alternating path and then the change status and then I drew the improved matching. After that I did another alternating path and changed status however I used my improved matching for that, and finally that's how i got my complete matching. Did I do it right if not how much mark would I lose.

Reply 215

Nonomomo

Original post by Arsey

I have uploaded my solutions to the other time zone paper in the first post.

Thank you so much for posting the international model answer :smile:

cheers

Reply 216

rber

Hi for the part b question on matching I first found an alternating path and then the change status and then I drew the improved matching. After that I did another alternating path and changed status however I used my improved matching for that, and finally that's how i got my complete matching. Did I do it right if not how much mark would I lose.

if anyone can reply that will be great. thanx

Reply 217

talstactician

Original post by rber

Hi for the part b question on matching I first found an alternating path and then the change status and then I drew the improved matching. After that I did another alternating path and changed status however I used my improved matching for that, and finally that's how i got my complete matching. Did I do it right if not how much mark would I lose.

if anyone can reply that will be great. thanx

That's exactly what you are meant to do, so full marks (assuming you got the complete matching right at the end :tongue:

)

(edited 10 years ago)

Reply 218

Caribbeantwist

12

Original post by niki135

Ah I hope we didn't do that bad and still manage to get our A! From what my friends were telling me, S1 started off well but got harder at the end. Hopefully boundaries are low!