OCR (Non MEI) D2 Wednesday 25th May 2016

for the last question I only put the route but not the minimax value, is that ok?

aha I was not looking forward to that question, I was expecting another bird sanctuary or dog houses.... But yeh I know how you feel, I had C2 before that exam and started to get lazy in D2

At least I have another 3 weeks until I need to deal with the trauma of simplex....

Xsanda’s solutions:

1) Matching
i) JF=3-ND=4
1:MA
2:-
3:JF
4:ND
5:JA
6:MJ
ii) SO=5-JA=2
1:MA 2:JA 3:JF 4:ND 5: SO 6:MJ
iii) 3=JF,4=ND,5=SO always
1:MJ 2:MA 3:JF 4:ND 5: SO 6:JA

2) Flow
i) FT = 2, DT = 4, cut = 9
iia) SCBFT +2 (given)
b) SCFBAEDT +1
iii) 8, with cut {SABCF}{DET} of value 8

3) Hungarian
i) Add dummy column X with 100 in each
Reduce rows -86, -91, -88, -98
Reduce cols -0,-2,-0,-2
ii) AS, BT, CL, no match for D, £271 cost
iii) CS, BT; AL costs £83

4) Rock paper scissors
i) scissors with paper: gain of 1, loss of 2: 1 + (-2) ≠ 0
ii) playsafe: scissors
iii) scissors 2-2p-4q, paper 3p+2q-2, rock 2q-p
iv) p=0.5, q=0.25, rock = 0.25

5) critical path analysis
i) F and H also critical
ii) A: -, B: -, C: -, D: A, E: BD, F: BCD, G: E, H: EF, I: GH, J: H
iii) 60 mins, critical ABDEHJ
iv) allocation for 3 people
v) allocation for 2 people
vi) A is critical, but so is B, which happens at the same time, so must reduce both to gain 5 minutes. 200+400=£600. Best is H and J: £500+£500 = £1000

6i) (0;0)-(1;1)-(2;1)-(3;0)-(4;0): weight 7
ii) 1 point
iii) (0;0)-(1;0) 1
(0;0)-(1;1) 2
(1;0)-(2;0) 1
(1;0)-(2;1) 1
(1;1)-(2;0) 2
(1;1)-(2;1) 1
(2;0)-(3;0) 0
(2;0)-(3;1) 0
(2;1)-(3;0) 2
(2;1)-(3;1) 0
(3;0)-(4;0) 1
(3;1)-(4;0) 2
iv) (0;0)-(1;0)-(2;0)-(3;0)-(4;0): 1 point per round maximum

Xsanda’s solutions:

1) Matching
i) JF=3-ND=4
1:MA
2:-
3:JF
4:ND
5:JA
6:MJ
ii) SO=5-JA=2
1:MA 2:JA 3:JF 4:ND 5: SO 6:MJ
iii) 3=JF,4=ND,5=SO always
1:MJ 2:MA 3:JF 4:ND 5: SO 6:JA

2) Flow
i) FT = 2, DT = 4, cut = 9
iia) SCBFT +2 (given)
b) SCFBAEDT +1
iii) 8, with cut {SABCF}{DET} of value 8

3) Hungarian
i) Add dummy column X with 100 in each
Reduce rows -86, -92, -88, -98
Reduce cols -0,-2,-0,-2
ii) AS, BT, CL, no match for D, £271 cost
iii) CS, BT; AL costs £83

4) Rock paper scissors
i) scissors with paper: gain of 1, loss of 2: 1 + (-2) ≠ 0
ii) playsafe: scissors
iii) scissors 2-2p-4q, paper 3p+2q-2, rock 2q-p
iv) p=0.5, q=0.25, rock = 0.25

5) critical path analysis
i) F and H also critical
ii) A: -, B: -, C: -, D: A, E: BD, F: BCD, G: E, H: EF, I: GH, J: H
iii) 60 mins, critical ABDEHJ
iv) allocation for 3 people
v) allocation for 2 people
vi) A is critical, but so is B, which happens at the same time, so must reduce both to gain 5 minutes. 200+400=£600. Best is H and J: £500+£500 = £1000

6i) (0;0)-(1;1)-(2;1)-(3;0)-(4;0): weight 7
ii) 1 point
iii) (0;0)-(1;0) 1
(0;0)-(1;1) 2
(1;0)-(2;0) 1
(1;0)-(2;1) 1
(1;1)-(2;0) 2
(1;1)-(2;1) 1
(2;0)-(3;0) 0
(2;0)-(3;1) 0
(2;1)-(3;0) 2
(2;1)-(3;1) 0
(3;0)-(4;0) 1
(3;1)-(4;0) 2
iv) (0;0)-(1;0)-(2;0)-(3;0)-(4;0): 1 point per round maximum

All spot-on apart from the 2nd row in Q3(i) is reduced by 92, not 91.

Updated, thanks Mr M Jr

Hi bassala,
That's exactly right for the first part of the question, but for the second part, you need to find the total cost, as £1000

All spot-on apart from the 2nd row in Q3(i) is reduced by 92, not 91.

All spot-on apart from the 2nd row in Q3(i) is reduced by 92, not 91.

hello, please could you estimate how many marks I'll lose for not making the negatives positive on the last - dynamic programming question? I got the correct route at the end and all the method should be right.... my table contains negatives though

i think i lost 3 marks excluding the final question, and am hoping this one mistake isn't detrimental and causes me to go below the 90 ums score.. :/

Probably drop 2 marks

Surprised the boundaries are so high for this. 62 for an A!