Year 12s: what will be the first way you research your future options? >>

Aqa d2 unofficial markscheme 24/06/2015

1a) Precedence table (2 marks)
A,B
B
B,C
D
D,E,F
G,H
G,H

1b) Early start time and late finish times (4 marks)
Both activities at the end should have a finish time of 28

1c) State critical paths (2 marks)
ADHJ BFHJ

1d) Float time for E (1 mark)
1

1e) Cascade diagram- start as early as possible (4 marks)

1f) Minimum completion time with 1 worker (1 mark)
65

1f) Minimum completion time with 2 workers and state an appropriate allocation of activities for each worker (something along those lines) (2 marks)
37?

2a) Play safe strategy for each player ( 3 marks)
First person- strategy A/C ?
Second person- strategy E

2b) Explain why there is not a stable solution (3 marks)
0 is not equal to -3 therefore no stable solution

2c) Explain why this is a suitable play of matrix for Christina? (4 marks)
Zero sum game- gain of one= loss of other
Idea of dominance

3) Hungarian algorithm- (11 marks)
36.82

4a) Initial flow ( )
100

4b) Maximum flow ( )
118

4c) State the edges of the cut ( )

4d The Vertex G can now only allow 30 litres of water through. What is the new maximum flow? (2 marks)
113

5) Give simplex tableau - do 2 iterations and find values ( )
Pmax= 52, x=0, y=12, z=4, s=0, r=2, t=0

6) Dynamic programming question about Tom
a) ACFJK
b) ACGIK
c) 2.6

7a) Optima mixed strategy p=1/4
b) x=1 (2 marks)

(edited 8 years ago)

Scroll to see replies

4 d) is 113

Original post by 2014_GCSE

4 d) is 113

Great thanks- do you remember the q and the number of marks? I'll update.

Reply 3

2014_GCSE

Original post by Mitzy09

Great thanks- do you remember the q and the number of marks? I'll update.

The Vertex G can now only allow 30 litres of water through. What is the new maximum flow? (Something like that)

2 marks.

Reply 4

majka

I can't understand your answers for 1a...

They asked about the predecessors, right? So shouldn' t it be:
-
-
-
A,B
B
B,C
D
D,E,F
G,H
G,H

D: ?

Reply 5

Mitzy09

Original post by majka

I can't understand your answers for 1a...

They asked about the predecessors, right? So shouldn' t it be:
-
-
-
A,B
B
B,C
D
D,E,F
G,H
G,H

D: ?

Sorry, I wrote it as one. Changed it for you :smile:

Reply 6

majka

Original post by Mitzy09

Sorry, I wrote it as one. Changed it for you :smile:

Thanks! (: Was D necessary to write as well?

Reply 7

majka

For 2a) I had: first person A, C second person E

Reply 8

CoIIins

For 1e. Are you allowed to do a cascade even though it said gantt? I did a cascade because i was unsure what a gantt was.

Reply 9

Mitzy09

Original post by CoIIins

For 1e. Are you allowed to do a cascade even though it said gantt? I did a cascade because i was unsure what a gantt was.

are they not the same thing?

Reply 10

CoIIins

Original post by Mitzy09

are they not the same thing?

I have no idea! I hope they are. As far as i was aware Gantt starts a new line for every task? But cascade doesn't, they are very similar and I imagine you would be allowed either.

(edited 8 years ago)

Reply 11

Mitzy09

Original post by majka

For 2a) I had: first person A, C second person E

Did you have to put A/C or could you put either?

Reply 12

majka

Original post by Mitzy09

Did you have to put A/C or could you put either?

I put both but I'm not sure if this is correct. On the one hand they asked about one strategy for each. On the other hand -3 repeated so it seems logically that there are two possible options...

Reply 13

Mitzy09

Original post by majka

I put both but I'm not sure if this is correct. On the one hand they asked about one strategy for each. On the other hand -3 repeated so it seems logically that there are two possible options...

Okay I'll update thanks! Do you think it would be accepted if you just put A instead of A/C?

Original post by CoIIins

I have no idea! I hope they are. As far as i was aware Gantt starts a new line for every task? But cascade doesn't, they are very similar and I imagine you would be allowed either.

Yh because on past papers I've seen the questions ask for a cascade diagram but sometimes in brackets they also write gantt chart, so I assumed it meant the same thing :smile:

Reply 14

majka

One more question...

In ex 3 I forgot completely about adding the dummy column and reduced columns and rows and then used Hungarian on the original one.

Do you think that I will lose all 11 points?

Reply 15

bencurnow

Question 1g) [you labelled it as 1f in the markshceme]

Surely this?

Worker 1: A (0-7) D (7-13) E (13-20) G (20-25) I (26-34)
Worker 2: B (0-5) C (5-9) F (9-17) H (20-26) J (26-35)

Then the new time would be 35 hours?

(edited 8 years ago)

Reply 16

Mattw19998

What athletes matched which legs on the hungarian algorithm? Thanks