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# Edexcel D1 - 17th June, 2016 [Exam discussion] watch

1. (Original post by target21859)
Here's the mark scheme
June 2014, final question? What a nightmare
2. (Original post by SeanFM)
June 2014, final question? What a nightmare
Yeah I thought I understood but I just realised I actually don't. If you know how to do it could you explain it to me please? There's different methods such as point testing and the gradient of the line but I don't understand either of them.
3. (Original post by target21859)
Yeah I thought I understood but I just realised I actually don't. If you know how to do it could you explain it to me please? There's different methods such as point testing and the gradient of the line but I don't understand either of them.
I sat the exam and left this question blank I'll have a look again, I thought someone explained it above.
4. (Original post by SeanFM)
I sat the exam and left this question blank I'll have a look again, I thought someone explained it above.
Yeah partially. He gave me a hint as to how to go about it and I thought that I solved it but I just realised that I didn't. I think the grade boundaries were quite low that year. It was like 71 for full ums.
5. (Original post by target21859)
Yeah partially. He gave me a hint as to how to go about it and I thought that I solved it but I just realised that I didn't. I think the grade boundaries were quite low that year. It was like 71 for full ums.
Well you know that the function at A is less than D so that's your first inequality.. you somehow have to deduce that C is less than B, but not sure how seems countet intuitive if you look at the graph.
6. (Original post by target21859)
Yeah partially. He gave me a hint as to how to go about it and I thought that I solved it but I just realised that I didn't. I think the grade boundaries were quite low that year. It was like 71 for full ums.
The profit line can be between the gradient BA and CD, if it were any steeper, then it would cross B first, if it were any shallower, it would C last. The gradient of BA is -4 and the gradient of CD is -2.

Now,the profit line can be written as, where is some constant, so the gradient of the profit line is

This can be between the gradient of BA and CD, it can't equal these gradients however, as the profit line would cross all points on the line, meaning all points on the line would be the minimum/maximum.

So, and . Rearrange the inequalities , remembering to reverse the inequality sign when multiplying or dividing by a negative number.
7. (Original post by NotNotBatman)
The profit line can be between the gradient BA and CD, if it were any steeper, then it would cross B first, if it were any shallower, it would C last. The gradient of BA is -4 and the gradient of CD is -2.

Now,the profit line can be written as, where is some constant, so the gradient of the profit line is

This can be between the gradient of BA and CD, it can't equal these gradients however, as the profit line would cross all points on the line, meaning all points on the line would be the minimum/maximum.

So, and . Rearrange the inequalities , remembering to reverse the inequality sign when multiplying or dividing by a negative number.
Thank you that explained it really well. It was really appreciated.
8. What definitions do we need to know?
9. For activity networks, does the number ordering for the nodes matter?
10. (Original post by Nikhilm)
For activity networks, does the number ordering for the nodes matter?
For constructing them no, the dependencies have to be correct. For Critical Path Analysis, the order of labelling matters.
11. (Original post by Jules12345)
What definitions do we need to know?
https://qualifications.pearson.com/c...hs_Issue_3.pdf

Page 100
12. (Original post by NotNotBatman)
For constructing them no, the dependencies have to be correct. For Critical Path Analysis, the order of labelling matters.
Thanks! Would you get marks deducted for curvy lines when constructing?
13. (Original post by Nikhilm)
Thanks! Would you get marks deducted for curvy lines when constructing?
No, that would be fine.
14. (Original post by NotNotBatman)
No, that would be fine.
How sure are you about that? Cos a couple of mark schemes have drawn curvy lines, but the book says the convention is straight lines and I remember seeing an examiners report discouraging curvy lines, I'll try and find a link to it
15. (Original post by Nikhilm)
How sure are you about that? Cos a couple of mark schemes have drawn curvy lines, but the book says the convention is straight lines and I remember seeing an examiners report discouraging curvy lines, I'll try and find a link to it
I've seen about 4 questions asking for the construction of an activity network, in the marking scheme it never says anything about curvy lines, whats marked are the dependencies and dummies. My teacher has also told me that it doesn't matter.
16. can someone link me the 2015 d1 paper with the answer booklet and mark scheme please?
17. (Original post by HarveySpecter97)
http://qualifications.pearson.com/co...e_20150609.pdf
18. when formulating a linear programming problem, are you supposed to put the whole summary like when it says: minimise/maximise "objective function"
subject to: "constraints"

even if you've wrote it out before hand? idk if people know what i mean, like in edexcel textbooks for example page 118 from example 3, they've basically wrote the decision variables, objective function and constraints and then summarised it in the subject to stuff.
19. (Original post by NotNotBatman)
I've seen about 4 questions asking for the construction of an activity network, in the marking scheme it never says anything about curvy lines, whats marked are the dependencies and dummies. My teacher has also told me that it doesn't matter.
How about lines that cross over each other?
20. Hey guys how do I schedule a project without a gantt chart beforehand? An example is this question part D!
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