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RoughDECISION 1 EDEXCEL JUNE 17TH MARKSCHEME w/Explained Answers

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 :frown:

- 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 :smile: