You are Here: Home >< Maths

# D+D Help Needed! watch

1. I'm taking D+D1-the old MEI syllabus-tomorrow, and need to get at least 50% for an overall A in further maths A-level. However, our maths group has basically been left to learn it by ourselves as it's so easy, and because I hate D+D so much I havn't done this, which is quite silly of me-but I'm sure most of you agree D+D is a waste of time! I would have preferred to do M4, but we didn't have that option.
Anyway, I can do most of the critical path stuff and all that inequality maximisation business (linear programming I think it's called?) pretty easily, but would like to learn a couple of algorithms incase they come up in the exam.
So, my question is what algorithms come up most frequently in the exam (bear in mind I only have one past paper)?

And also, as D+D is considered to be an easy paper, does this mean grade boundaries are normally set very high- ie. is 80 UMS marks likely to be significantly more than 80% raw marks? If so then I may have to do some more work!

sam
2. They like the one where you find the shortest route from A to G- (I forget the name as I did it last year) and they have to give you an insert for it, and there are boxes to fill in by each node, with which position in the chain it is, the distance from A and working at the bottom- know the one? It might be Dijkstre's.. not sure.
3. (Original post by majikthise)
Anyway, I can do most of the critical path stuff and all that inequality maximisation business (linear programming I think it's called?) pretty easily, but would like to learn a couple of algorithms incase they come up in the exam.
maximizing or minimising is called linear programming

(Original post by naystar)
They like the one where you find the shortest route from A to G- (I forget the name as I did it last year) and they have to give you an insert for it, and there are boxes to fill in by each node, with which position in the chain it is, the distance from A and working at the bottom- know the one? It might be Dijkstre's.. not sure.
its djiskas algorithm where the boxes are order of labelling, working values and the working values.
4. ok, sounds like I should learn djiskas algorithm- thanks.

Does anybody know the raw mark grade boundaries for recent papers?
5. my teacher told me that decision maths exams are hard.

Last year for D1 if you get a mark of about 52 then u get an A.
It would be similar this year so i wouldn't worry bout it that much.
6. Isn't the total number of marks 60 though?
Which means for an A you need 86.7%, higher than "normal"?
7. Mine was out of 75 though if i remember correctly. (Edexcel)
8. For decision maths there are a few different things you will probably need to know.

Linear Programming / Simplex (Maybe, some people say it never comes up but no harm in being prepared)

Algorithms (Prims, Dijekstra's (Can't spell it), Chinese Postman, Kruskals does the same as Prims but it doesn't hurt to know both.)

Basically each algorithm does a different thing, for example Prims and Kruskals find the minimum connector, Dijekstras finds the shortest route and the chinese postman algorithm finds the minimum length when traversing every arc.)

There might be a question on the shuttle sort or bubble sort methods of arranging numbers.

Also check out the First fit and first fit decreasing algorithms, useful in finding out how many pipes a person needs to cut 8 different lengths for example.

I'm not 100% about what's on your syllabus, i had my OCR Decision 1 paper about a week or so ago, and it was a hard paper.

I'm sure i haven't put everything down, that's just all i can remember at the moment.
9. Well taking the coursework into account for the MEI old syllabus that would be 75marks so about 69% which is actually really low,
But from last years paper which we did as a mock, 33 was an A grade which was just over 50% but that was because so many people didnt get alot of hte marks available

And if i remember correctly, the bigger questions in section B are normally critical path analysis, linear programming and simulation.
But just read through most hte book and work through all the algorithms and remember which one is which, its normally only prims, kruskals or sometimes Dijkstra's
10. I'll try to learn as much of that as I can before tomorrow!
I'm sure 50% shouldn't be to difficult to get, but it would suck if I got all A's up to P6 and then lowered my grade due to D+D, hehe.

thanks again for the replies.
11. Try to leave the long questions last which should give u enough time to get all the easy marks in the exam.

Anyway good luck.
12. And just read the text in the chapters as somethings come up which are only in the texts of the chapter, not in hte summary at the end of hte chapters, i'll be sitting this exam too, in my mock i got 1mark off an A and i hadnt learnt ANYTHING on simulation so im just brushing up on them, the algorithms and reading through the graphs chapter again.
13. We didn't get taught the simplex method for linear programming, and its not in the Mei syllabus and text book.
We've been told to do it graphically with the inequalities (constraints)

Yet I'm trying to learn the simplex, because a question came up in the past exam papers in which there were 3 variables and nobody got it right, because it couldn't be done graphically!

So should I learn the simplex, considering that if I don't and if a 3-variable linear programming question does come up, I'll loose 7-9 marks?
14. Well you wont lose marks, and if its not in the syllabus how can they mark you down for not doing something that isnt in the syllabus,
but normally its just two variables with 3inequalities where one becomes irrelevant and one profit/maximising equation
15. (Original post by Vijay1)
We didn't get taught the simplex method for linear programming, and its not in the Mei syllabus and text book.
We've been told to do it graphically with the inequalities (constraints)

Yet I'm trying to learn the simplex, because a question came up in the past exam papers in which there were 3 variables and nobody got it right, because it couldn't be done graphically!

So should I learn the simplex, considering that if I don't and if a 3-variable linear programming question does come up, I'll loose 7-9 marks?
The simplex algorithm i think should be revised. It could be a few marks in the exam or it could be a 15 marka.

The pattern is always the same so if u can do it the first time, u can do it for a lot of other times.
16. (Original post by geekypoo)
Well you wont lose marks, and if its not in the syllabus how can they mark you down for not doing something that isnt in the syllabus,
but normally its just two variables with 3inequalities where one becomes irrelevant and one profit/maximising equation
yes but I've seen someone do the simplex method, and it looks so neat if done properly, I really would like to learn it, so I guess I will.
17. But thats like using methods from p6 to solve matrices in p4, is it not? the whole reason about D&D1 being a 1 is that its supposed to be alot simpler and easier than later things, You may get the answer marks but no method marks right??
18. My teacher told me that as long as you use correct maths, they will mark you correctly for it (unless the question says "Show...by method of...." obviously). I hope this is right, as I used some more advanced vector methods in P3/4 that weren't on the syllabus.
19. Yeah, as long as it does not specify a way to work it out in the question, you can get the marks using any mathematical method.

What might happen with simplex is that they will say "Show this problem in an initial simplex tableau" this would mean you need to manipulate your constraints and place them in a simplex tableaux. That might be worth something like 5 marks or so.

Then they may say "Show the optimised simplex tableau" which might be worth something like 6 marks or so.

I'd say revise it, if you have seen it in past papers from your syllabus then they can put it in i assume, but you say it isn't in your syllabus which is confusing if they have put it in older papers. In the OCR D1 paper a question worth about 15 or so marks came up on simplex, and i got it completely wrong, regretting that now heh.
20. basically...
you need bubble and shuttle sorts
know types of graph (is it a walk, a path, a digraph, complete, isomorphic...etc)
you need BOTH kruskal and prim for minimal spanning tree (kruskal is choose an arc, prim is choose a node)
Djikstra's for shortest path is a BIG BIG hit for exam questions
Critical path (including independent and interfering float though don't concentrate on the float or cascade charts)
Then linear pragramming

That is all you need for MEI D1. If you learn that, then with some time management and common sense then you'll do fine.

If I had little time I would learn Djikstra's first, including a lot on critical path and resource needs. Then Prim and Kruscal. Then the linear programming. Then graph types then the rest. You don't need simplex tableau

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 19, 2005
The home of Results and Clearing

### 1,068

people online now

### 1,567,000

students helped last year
Today on TSR

### University open days

1. Sheffield Hallam University
Tue, 21 Aug '18
2. Bournemouth University
Wed, 22 Aug '18
3. University of Buckingham
Thu, 23 Aug '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams