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# OCR (not MEI) D1 24th May 2013 watch

1. (Original post by sj_1995)
I think you had to delete the arc that had now been destroyed by the landslide (since the total weight would no longer be 224)
Do you think if you put he can only walk 3km because then he will be wiped out be a landslide will count?!

I can't believe the D1 exam only lasts 90 minutes. If they had any common sense they would give us 1hr 45 mins or 2hrs for this, none of the other maths exams have this problem.
2. (Original post by JASApplications)
What did people get for that little 2 marker where you had to find by how much CE would need to be shorter for that route to be used?
4?
i got CE<4
so CE=3
3. (Original post by metaltron)
Do you think if you put he can only walk 3km because then he will be wiped out be a landslide will count?!

I can't believe the D1 exam only lasts 90 minutes. If they had any common sense they would give us 1hr 45 mins or 2hrs for this, none of the other maths exams have this problem.
It wouldn't surprise with D1!

I completely agree, I do FP2 and FP3 and can (usually) complete them on time, with checking time to spare. This paper was ridiculously time consuming, especially the algorithm question (albeit it wasnt the hardest question on the paper) which can easily cause you to rush and panic.
4. (Original post by sj_1995)
I think you had to delete the arc that had now been destroyed by the landslide (since the total weight would no longer be 224)
Yeah, that was the question where you had to delete arcs AC and CE or something right?
5. (Original post by DarkPeople)
Yeah, that was the question where you had to delete arcs AC and CE or something right?
Oh dear...
6. What about the one where you had to predict the values of f and m without doing any working, on the algorithm question?
7. daaaammmm I found that paper a killer. Was really hoping for an A at the end of A2 but if I get less than a C in this exam thats not going to be possible. The last question took so much time!!! And six marks for two iterations??? usually its like 10... but its probably a blessing in disguise as I only had time to do one iteration. The kurshkals and Djikstras questions went well, as did the first one... but the 2nd qn, the algorthim, and the last one killed me. Hope to god grade boundries are low!!! This exam should have been 1:45 at least...
8. I swear it was 90 and 6 for the new algorithm thing because they were HCF and LCM things?
I remember it was like :

30 x 3 = 90
18 / 3 = 6

I dunnooo...that was my connection anyways...

I also remember:

Bubble sort (time consuming but simple enough)
Eulerian graph with 2 nodes of order 4
Eulerian graph with 1 node order 6 and the rest order 2

The algorithm with F and M gets stuck in a loop if you reverse B and A

If you input 12 and 8 ... I think it's 48 and 2 but I could be entirely wrong...

Kruskal's was fairly simple...I came up with 31 k and ABCF I think??

Nearest neighbour gets stuck at G if you start at A...

Difference of 3k to be included in MST

Linear programming vertices of FR (0,0), (4,0), (6,3), (4,4.5)
P= 0, P=20, P=54, P=56

Simplex just crapped everything up...pivot for first iteration was 8 tho...
9. (Original post by CocoTango)
I swear it was 90 and 6 for the new algorithm thing because they were HCF and LCM things?
I remember it was like :

30 x 3 = 90
18 / 3 = 6

I dunnooo...that was my connection anyways...

I also remember:

Bubble sort (time consuming but simple enough)
Eulerian graph with 2 nodes of order 4
Eulerian graph with 1 node order 6 and the rest order 2

The algorithm with F and M gets stuck in a loop if you reverse B and A

If you input 12 and 8 ... I think it's 48 and 2 but I could be entirely wrong...

Kruskal's was fairly simple...I came up with 31 k and ABCF I think??

Nearest neighbour gets stuck at G if you start at A...

Difference of 3k to be included in MST

Linear programming vertices of FR (0,0), (4,0), (6,3), (4,4.5)
P= 0, P=20, P=54, P=56

Simplex just crapped everything up...pivot for first iteration was 8 tho...

We all have more different answers than similar ones. I honestly think the grade boundaries have to be low for this. Something like 48/49/ out of 72 for an A because I've not seen a D1 paper take so much damn time.
10. (Original post by BawanHama)
daaaammmm I found that paper a killer. Was really hoping for an A at the end of A2 but if I get less than a C in this exam thats not going to be possible. The last question took so much time!!! And six marks for two iterations??? usually its like 10... but its probably a blessing in disguise as I only had time to do one iteration. The kurshkals and Djikstras questions went well, as did the first one... but the 2nd qn, the algorthim, and the last one killed me. Hope to god grade boundries are low!!! This exam should have been 1:45 at least...

Don't worry. I missed out probably more marks then I gained. I skipped at least 2 parts of a question because I thought I'd have time to go back, and I messed up on a cycle and also on Route Inspection where I forgot to delete the arcs from the land slide.
11. Probably the second worst D1 paper I've ever done. The worst was when I took it at AS, lol
12. (Original post by Zakee)
Don't worry. I missed out probably more marks then I gained. I skipped at least 2 parts of a question because I thought I'd have time to go back, and I messed up on a cycle and also on Route Inspection where I forgot to delete the arcs from the land slide.
Lool sorry but may I ask why you've chosen your username - is it your nickname? Cos it's how you pronounce my name (Zaki (which is a nickname of Zakaria)) which is not very common.

Hah - Like a lot of people I seemed to also incorrectly get 88 on the last Q - I wonder what mistake we all made. Very annoying. I was completely rushing that one too - Anyway I also made a mistake on that landslide question -.-

What do u reckon the grade boundary will be? The highest one I've seen was 61 but there have been 40 - somethings.
13. What I can remember:

Bubble sort:
1i) First pass correct with correct comparisons and swaps.
ii) Second and third pass correct.
iii) Pass 1 - 4 swaps
Pass 2 - 3 swaps
Pass 3 - 2 swaps
Pass 4 - 1 swap
Pass 5 - 1 swap

Eulerian Graphs:

2

i) Maximum = 6 arcs
Minimum = 2 arcs

ii) Correct drawing with one vertex order 6.

iii) Order = no. of arcs = 10 x 2 = 20

iv) Correct drawing, two vertices with order 4 and other order 2.

3.i) Trace the algorithm, outputs 6 and 90.
ii) Fill in table, values the same as in part i) until it comes to dividing by A. Nevertheless outputs are still 6 and 90.
iii) 4 and 24

4i) Kruskal's's
Start from B to get a cycle of weight of
Alteration to obtain a length of 69 km.

5i) Dijkstra's
ii) Chinese Postman on reduced network.

6i) Correct drawing.
ii) x = 4, y= 4.5 , P= 56
iii) Try all integer values of x with their respective y-values. Obtain P = 54.
iv) To get constraint in the form ax+by <= c, as algorithm can not be used for greater than constraints.
v) Initial Simplex tableau
ii) Can't remember the first values, but you will then verify for non-integer values that P = 56, when x = 4 and y =4.5
14. For the second iteration, what pivot value did people use? I think I pivoted on 9/4 in the x column but I don't think I ended up with 56!
15. (Original post by Zak_Dubai)
Lool sorry but may I ask why you've chosen your username - is it your nickname? Cos it's how you pronounce my name (Zaki (which is a nickname of Zakaria)) which is not very common.

Hah - Like a lot of people I seemed to also incorrectly get 88 on the last Q - I wonder what mistake we all made. Very annoying. I was completely rushing that one too - Anyway I also made a mistake on that landslide question -.-

What do u reckon the grade boundary will be? The highest one I've seen was 61 but there have been 40 - somethings.

It's actually my real name.

Erm, well. I think 51 is an A for this paper. Honestly, the amount of time it took, and so many people are saying they ran out of time/wrong answers/too long/messed up.

Roughly around 50. If it's anything above 56+ for 80 UMS, then something has seriously gone wrong and I will just weep.

The 61 was because the year before (June 2011) OCR made a mistake on the paper so a question was unsolvable and they made the paper far more easier for those doing resits in order to allow them to achieve the respectful grades as I guess it was their way of repenting. However, for the last three years (June Papers)

80 UMS has been 51 (June 2010), 44 (June 2011), 49 (June 2012). As June 2011 was simpler than this paper, I can only hope 50 is an A or something like that.
16. Where's Mr M !!!? can you upload the answers ASAP
17. (Original post by Zakee)
It's actually my real name.

Erm, well. I think 51 is an A for this paper. Honestly, the amount of time it took, and so many people are saying they ran out of time/wrong answers/too long/messed up.

Roughly around 50. If it's anything above 56+ for 80 UMS, then something has seriously gone wrong and I will just weep.

The 61 was because the year before (June 2011) OCR made a mistake on the paper so a question was unsolvable and they made the paper far more easier for those doing resits in order to allow them to achieve the respectful grades as I guess it was their way of repenting. However, for the last three years (June Papers)

80 UMS has been 51 (June 2010), 44 (June 2011), 49 (June 2012). As June 2011 was simpler than this paper, I can only hope 50 is an A or something like that.
I don't think it will be 50/72 for an A I think the max it can be is 56/72 but then again the content wasn't that difficult lets be honest, just the algorithm question that wasn't that difficult I must say compared to previous years. But the mark to time ratio was totally wrong I must say i don't know what OCR was thinking, a very lengthy paper indeed. And btw it was 44/72 in June 2010 b/c of the mistake they made.
18. For the linear programmin question the one were u had to draw it out, where did you guys get the feasible region ? Was it between the centre and 2 other points?
because i got two triangles but i found the feasible regoin to be between the centre and 2 other points, but i wasnt sure if its right?
19. (Original post by waheed786)
Where's Mr M !!!? can you upload the answers ASAP
I don't do D1 - sorry!
20. I've got the paper, don't know when I'm allowed to upload it though, dont you have to wait a day or something?

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