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# AQA Mathematics MD01 Decision 1 – Friday 24th June [Exam Discussion Thread]

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1. (Original post by kingowl)
My teacher thinks it's gonna be a tough one and they're gonna throw some algebra in there (like the nearest neighbour questions that have come up before) but he's not sure where.
Any predictions?
I'm expecting a lot of tough graph theory questions ('cause AQA hate us this year)
Which paper had algebra in? I don't remember doing a paper like that recently

And yeah AQA always hate us, not just this year :P
2. Any advice on the 4 sorting algorithms??
3. Can anyone explain why the best lower bound for the travelling salesman problem is the highest option? I kind of get why the best upper bound is the lowest, but I don't get the lower bound rule.
4. (Original post by shmelissas)
Any advice on the 4 sorting algorithms??
Find the most illogical response and you'll get full marks
5. (Original post by yelash)
Can anyone explain why the best lower bound for the travelling salesman problem is the highest option? I kind of get why the best upper bound is the lowest, but I don't get the lower bound rule.
I think basically, there is no foolproof method or algorithm to find a solution to a travelling salesman problem.

We use two algorithms, nearest neighbour (UB) and lower bound to find a range of values that the solution, X, may lie in.

As we want this range to be as small as possible ( Lower bound < X < Upper bound)

The best lower bound is the highest LB. best UB is lowest UB
6. I find D1 the worse... even worse than D2...

IT'S NOT MATHS WHY DOES IT EXIST
7. After the horror that was C3 and C4 this'll be make or break for me and probably a lot of others.
8. (Original post by yelash)
Which paper had algebra in? I don't remember doing a paper like that recently

And yeah AQA always hate us, not just this year :P
Ah, we got set some questions which I assumed were from past papers but doesn't look like they are. Not sure where it's from, maybe another exam board, but this is a couple things which my teacher thinks might might come up (or something similar)

Spoiler:
Show
Spoiler:
Show
Spoiler:
Show
9. (Original post by User204395)
After the horror that was C3 and C4 this'll be make or break for me and probably a lot of others.
It's got to be better than C3...
10. When they ask you to draw the minimum spanning tree for the lower bound in the travelling salesperson problem, and they ask you what can you conclude from the graph, what are the general things you have to say? Is there anything in particular you need to look for? I never seem to get those questions
11. Often they expect you to pick up that the mst doesn't necessarily represent a tour (ie you can't go round all the edges and end up back where you started). Although the total weight of the mst is a lower bound for a minimum length tour, the tour it represents might not actually exist. This is also why the best lower bound is the highest lower bound (because it's more likely to actually exist). Hope this helped! 😊
12. (Original post by lucyjane_x)
When they ask you to draw the minimum spanning tree for the lower bound in the travelling salesperson problem, and they ask you what can you conclude from the graph, what are the general things you have to say? Is there anything in particular you need to look for? I never seem to get those questions
If your lower bound forms a Hamiltonian cycle it exists but if it doesn't then it's not a tour so doesn't exist
13. (Original post by kingowl)
Ah, we got set some questions which I assumed were from past papers but doesn't look like they are. Not sure where it's from, maybe another exam board, but this is a couple things which my teacher thinks might might come up (or something
Spoiler:
Show
Spoiler:
Show
Thx- I think something like that is fairly likely to be set, although i don't think the algebra will get any more complicated than this.
14. Anyone actually know graph theory? I understand the basics of it but think they'll throw in some horrible ones I can't do, banking on the fact these papers usually take me an hour so I'll have half an hour to think about graph theory lol, those algebraic answers are from AQA past papers and the concepts are just the same, just involving algebra, nothing to worry about in fact it's probs better
15. (Original post by Eisobdxhsonw)
Anyone actually know graph theory? I understand the basics of it but think they'll throw in some horrible ones I can't do, banking on the fact these papers usually take me an hour so I'll have half an hour to think about graph theory lol, those algebraic answers are from AQA past papers and the concepts are just the same, just involving algebra, nothing to worry about in fact it's probs better
I am useless with graph theory lol but I understand everything else
16. (Original post by lucyjane_x)
I am useless with graph theory lol but I understand everything else
Yeah same XD. My score basically depends on the amount of graph theory. My score= (75-marks available for graph theory question)
17. (Original post by kingowl)
Ah, we got set some questions which I assumed were from past papers but doesn't look like they are. Not sure where it's from, maybe another exam board, but this is a couple things which my teacher thinks might might come up (or something similar)
Could you post the answers to those questions as well plz?
18. (Original post by lucyjane_x)
I am useless with graph theory lol but I understand everything else
Hoping that If no one can do graph theory, the more of it there is the lower the 100ums mark will be haha, always seem to make a few silly mistakes here and there and end up scraping 90 ums, literally would rather do stats
19. also when you have an objective line such as -x + 2y for example, how do you draw this on the graph because you can't draw it on the negative axis as they never include it, so how do you make it positive?
20. Ugh I'm screwed for graph theory lol, I'm expecting loads of marks on it this year. Oh well.

(Original post by yelash)
Could you post the answers to those questions as well plz?
Hopefully this isn't too late haha
http://imgur.com/a/EnkZ3
(I think they're in the right order)

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