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

1. guys is there a formula for the maximum number of comparisons in a binary search?
2. (Original post by willroberts98)
predictions for tomorrow??
Flow charts and digraphs on Dijkstra/Prim's or something. I'm telling ya, it's gonna come up.

(Original post by EricPiphany)
Jack and Daniel are up late studying for D1.
Jack completes a bin packing problem and notes that the total wasted space is less the the size of a single bin.
Daniel claims that the solution is optimal, but Jack is skeptical. How should Daniel argue his case?
Optimal solution is the sum of every value divided by the bin size. So if it the bin size is 11kg and you have bits and pieces of Legos weighing 60kg all together, 60/11, you're gonna get 5.4, so 6 bins. There are cases where 7 might be the optimal number, because in the "unfilled" bins you are left with values which are all more than half of the bin, i. e. over 5.5, so you cannot mix and match to merge the bins.

(Original post by The Curious One)
Ahhh right forgot about that, thanks guys!!!
Also does it matter which order we use in placing non-critical activities in a Gantt/Cascade chart? If so, then what sort of order?
It's not alphabetical order, na na. You need to look at the table and use logic. There might be cases where you notice that in order to complete activity B, you must have finished A before, even though A doesn't have an arrow pointing at B directly.
3. Good luck tomorrow ...

Would be wise to take the shortest route to school so that you arrive by the latest start time ...

4. (Original post by SeanFM)
Good luck tomorrow ...

Would be wise to take the shortest route to school so that you arrive by the latest start time ...

depends what the float time is
5. (Original post by theoriginalrpr)
guys is there a formula for the maximum number of comparisons in a binary search?
Hmm, I wanna say if you have n values, it's going to be (n/2)-1 but that doesn't work for odd numbers. So I don't think there is a formula.
6. (Original post by theoriginalrpr)
guys is there a formula for the maximum number of comparisons in a binary search?
rounded up, where n is the number of items in the initial list.
7. In an activity network is the source node indicated by a 0 or a 1? The D1 book uses a 0 in the examples and then a 1 in the mixed exercise. Has anyone seen a markscheme that explicitly states which is correct or should I assume that both are acceptable?
8. (Original post by Midgeymoo17)
Yeah, it is little. Unfortunatley there was an autistic boy in my class who suddenly had a meltdown at the prospect of Mechanics and just could not do it so April the 17th teacher started S3 ( 4 weeks before S3 exam) with both of us so he did not have to sit M2 and I had an extra. But this was the time he was meant to be doing D1- hence kind of ran out of time. This said I think I might just of got an A* or a middle to high A in S3 so no water off my back.
woot woo! smart guy!
9. 0 for source node always
10. Everyone chill, stop revising, cos grade boundaries are relative. So if everyone stops now, the outcome will be the same - whatever will be will be!

... Just kidding, everyone start revise cos tomorrow is the exam OMG
11. Just need some clarification on something quick. Someone like NotNotBatman Help moi Pls <3

For Time say hour in the day If they asked you to find activities that must be completed at the 9.5th hour you take this right? (9.5th time )

For Days if they ask you which activities must be completed at 4th day Mid day you do this right ? (5.5th time)

Also If they ask us which activity must be completed on time blah blah, and the time lines up with the end of that activity say it was on time 9 here.
Would we put down both the events before and after that time"
12. (Original post by Edwarric)
0 for source node always
Thank you
13. Anyone know where the m2 thread is?

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14. The value of the source node is 0 so when calculating early/late event times you would start of with 0 however when drawing activity on arc diagram you would label the node as 1. Correct me if im wrong but thats what my teacher told me and what the mark schemes say however the textbook does say 0 for both.

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15. (Original post by Themathgeek)
Anyone know where the m2 thread is?

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http://www.thestudentroom.co.uk/show...3#post65848283
16. Help anyone please. Part B.

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17. (Original post by NoahMal)
Just need some clarification on something quick. Someone like NotNotBatman Help moi Pls <3

For Time say hour in the day If they asked you to find activities that must be completed at the 9.5th hour you take this right? (9.5th time )

For Days if they ask you which activities must be completed at 4th day Mid day you do this right ? (5.5th time)

Also If they ask us which activity must be completed on time blah blah, and the time lines up with the end of that activity say it was on time 9 here.
Would we put down both the events before and after that time"

1. Yes
2. It would be at 3.5, Gantt charts show elapsed time.
3.The activity after.
18. (Original post by NotNotBatman)
3.The activity after.
Could you please elaborate? I don't think I even understand the question.
19. (Original post by pecora)
Could you please elaborate? I don't think I even understand the question.
I think he means, what activities are being done at a certain time, where that time would be on the line of two critical activities.
20. Think I have a solid knowledge of all the basics but I've got a feeling there will be some really awkwardly worded questions that I won't know what to do. I also need to learn the definitions because I still can't define a 'graph' or a 'tree' xD

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