*Rough*DECISION 1 EDEXCEL JUNE 17TH MARKSCHEME w/Explained Answers

I'm pretty sure you could've done it in 4 bins not 5?


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Nah i am pretty sure now its 65. 75 was the second smallest pair, and for the 65 the path was tricky, so i think the others just didnt see it.(at least i hope so)

In some papers you get penalised 1 mark

How many marks were questions 2, 7 and 8?

Getting on this one as fast as possible. I hated this exam, everyone else found it good - maybe decision maths isn't for me but it'll be nice to see how your answers compare.

Question 1:
- A bipartite graph consists of 2 vertices, X and Y. Vertices can only be joined from X to Y, not joined from the same set I.e. X to X.
- It was the most confusing / long winded route I got it as. You were matching P with B.
P-A = ..... M - B and change state.

Question 2:
- Precedence table was with 3 dummies. I did get a nice looking one but I know I made one mistake. C and D were dependent on A. E and F were dependent on B. A and B were dependent on nothing and came from a node labelled O.
Remember to link the all up at the end to create a nice network.

Question 3:
- Quicksort with 10 numbers. I can remember 11 being shifted to the very end after the first pass. Make sure to label pivots clearly and to say that the source is complete.
- First fit decreasing got you 4 bins.
- Lowerbound was 4, the question was asking if it was optimal. Therefore, it was optimal.

Question 4:
- Ouput 135 implying 7 and 25 were multiplied together.
- 122 because using 1/2 would encounter negatives.
- 122 X 1/2 = 61.

Question 5:
Worried about this one - can't remember it well.
- 48 units in length.
- One with J 49 units in length.
- Missed out Prim's question and only noticed at end so rushed like mad - I got 87.
Answer is 82 I believe.
Question 6: Chinese postman
- Weight 459 but I put 460
- Look at one excluding F which was EH and 35 in length.
- 419 with a route with 21 nodes, starting at F and finishing at B.

Question 7:
- for answers of w,X,y,z (not in order) 4,11,17 and 22?
- Gantt chart - hate you - you had 4 critical values. I got 6.
- 5 workers as lower bound looking at day 12-14
- Scheduling = ran out of time / didn't bother really.

Question 8:
- 20x + 65y less than or equal to 520.
- Remember that X.y larger than equal to 0. Plot the points to get a region R - one of the equations I struggled with and I think it was something like:
-X + 24y larger than or equal to 24. I brought the X over and got 0,0 and 0,1 as my points. I don't think it interfered with the region - I may have got it wrong please tell me.
- Exact values you had to look at the point of intersection between 7x + 8y = 120 and 20x + 65y = 520.
I did simultaneous equations and got fractions - I checked there decimal points and it did look close to where V was. I got V to be the upper, right hand side point.

9 and 4 I got for the crates
People got 9 and 5
I ink the correct is 11 and 4.
I think I've done horribly on this paper, please help me add on to it to create a nice markscheme! I really wanted an A overall, think I may have not done enough in this module. Anywho, I will update ASAP and try my best to respond quickly. Good luck all

They do lol. It says so on the front page

Only an idiot draws diagrams in pen anyway

last question: 9x and 5y giving maximum capacity given the budget of 520 as it cost a total of 505

For Algorithm one, some people say because 1/2 for X will give a never ending result as u'd keep halving the X value ( giving: -/2 -/4 -/8 -/16 ....)

I agree with it even though I didn't get in the exam

What do you think the grade boundaries will be like? I totally screwed up this paper and I need an A overall, I guess I'm just going to have to ace C3 and C4 lol

Oh yes I suppose - grrr another 2 marks I may have dropped. But wasn't the input of the algorithm:
Is X odd
If yes, X = X-1
So inputting 1/2 would take you to that procedure which encounters negatives? Cannot remember it well enough