Edexcel D1 Jan 23 2013 Revision thread

We discussed this earlier and concluded that the way you lay out table doesn't matter as long as output is correct. Judging by how many lines you get you can work out when to move on to next line. Usually move onto next line when you go back to beginning of flow chart. But it honestly doesn't matter, don't worry about it.

Tips
1) When scheduling make sure you consider a) the lowest late event time in deciding which activity to do next and b) that the activity follows the activity before it. Eg don't put down d before c if d comes after c in activity network
2) When ordering for binary seach use quick sort rather than bubble
3) When trying to work out why you can't get complete matching look for 2 people who can only do the same job e.g a and b can only do activity 3. Or look for someone who does 2 jobs no one else can do, so that if they do one there is no one to do other e.g b can do 3 & 4 and no one else can do either.
4) When calculating late/early event time, remember early time has to be as high as it can be and late time has to be as low. Don't overlook dummies.

Final tip? Go to bed, for D1 you need to be sharp and well rested otherwise you'll make mistakes. Good luck all

By the way anyone know how to plot objective line? I do it by swapping x and y co-efficients. Any help would be appreciated.

If we use kruskals do we have to say "reject all other arcs" once finished?

unofficial markscheme any1?

What a coincidence that a trace table came up...
I personally found that to be the most annoying question in the exam.

When it asked what happens if E was -8 I had no idea so just wrote it would give the negative square root of 72...hope that's right

What did everyone write for the number of iterations for question 2?

should be right for the -8. The question said it gave the square root and it gives the negative answer so the negative the square root is the same surely.....

iterations i put 4 but no one seems to know if once you have one it counts as an iteration to look at it

i put in 5 iterations

Hi arsey thank you for the mark scheme

For question 1 i got NO,NO,yes did we had to state the values next to it, cause it said is so i thought either Yes or no would be fine? second question on route inspection the 11600£ i did multiply 9 arcs x 80 will that get 1 mark? in route insepction the 6 marks how much is method mark you can get? Lastly, for the route in dijakstra did we have to state 29? i gave the route

Well, getting a B was a bit of a WTF moment. I know I lost 1 mark, but I thought I got the rest! Time to get mah paper back. For curiosity's sake.

D1 is such an odd module.