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# D1 Ocr Mei June 2012 Official Discussion

Maths exam discussion - share revision tips in preparation for GCSE, A Level and other maths exams and discuss how they went afterwards.

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1. Re: D1 Ocr Mei June 2012 Official Discussion
Surely minimum time will be 15.5 not 14, 5.5 to prepare batch and 10 to bake?
2. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by JackJones1186)
Surely minimum time will be 15.5 not 14, 5.5 to prepare batch and 10 to bake?
ye but its 14 when u draw the network.. u know when it says the critical activities and stuff
3. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by JackJones1186)
Surely minimum time will be 15.5 not 14, 5.5 to prepare batch and 10 to bake?
For the CPA activity on arc network I got 14 minutes as the minimum duration, but for one person on their own I got 15.5
4. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by Laura5494)
For the CPA activity on arc network I got 14 minutes as the minimum duration, but for one person on their own I got 15.5
yes thats what i also got... however it could have been just 5.5 for one person because the question said that the final activity took no ppl to do but yeah 15.5
5. Re: D1 Ocr Mei June 2012 Official Discussion
for random numbers does it matter which order you do them in
eg:
0 ---- single
1-8 ----- double
9 ------reject

OR

0-7 ----- double
8 ----- single
9 ------reject

as the both give different answers?
are both marked as correct?
6. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by amg_22)
for random numbers does it matter which order you do them in
eg:
0 ---- single
1-8 ----- double
9 ------reject

OR

0-7 ----- double
8 ----- single
9 ------reject

as the both give different answers?
are both marked as correct?
ye thats fine... you will definitely get the marks don't worry.. what did you get for the probability at the end?
7. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by sreddy17)
ye thats fine... you will definitely get the marks don't worry.. what did you get for the probability at the end?
i did single before double and probability 1/3

through 5 simulations: 0,1/3,1/3,1/3,2/3 (not in that order)
8. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by amg_22)
i did single before double and probability 1/3

through 5 simulations: 0,1/3,1/3,1/3,2/3 (not in that order)
how can you only have 3 bags left!!! there should be 6 bags left after 4 days if he picks one out each day!! surely
9. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by sreddy17)
Hi guys, I will do an unofficial mark scheme from what I can remember:
1.) draw network, then it was length 8 and a,c,e,g or something can't remember exactly but it had 4 arcs.

2.) relatively straightforward.
- application something to do with differentiation
-root 5 why is it included... not sure.

3.) For this graph theory question I can't remember exactly what I had but for part 2, i had one circle with a circle in it. and i had a little circle just touching the big circle.

4.)X = number of motors of type X made
etc
inequalities: there was one with x>5 and y>5 (greater than or equal to)

and 2 more i cant remember...

the max profit was where the two lines intersected.
for the last part the inequality changed and u just had to plot and give integer values.

5.) probably the hardest question, but bcoz it said 9 bags... u had to reject 9, and assign 0-7 to doubles and 8 to single.

and i got 0.6 as final probability for last question.. i added all my probs up i had 4 (4/6) and one 2/6

6.) 14 minutes was min time, after you draw the network.. and critical activities i can't remember
1 dummy used
took 2 ppl to do it in min time
min time for one just add them all up 5.5 i think( excluding the 10 one h) or 15.5 if u add h on, question didn't really make it that clear.
and then u had to draw a critical network showing the 5.5 then the 10 then he 5.5 again and 10 three times...

CANT REMEMBER MUCH ELSE
Graph one, got 1500 then 1450 as optimum profit.

0.6 for final probability

14min,2 people, 5.5 (exclude 10 I believe),

If buns go in one at a time its 5.5 + 3(10) since you can prepare whilst baking.

Then its 3(5.5) + 10 IF all together.
10. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by sreddy17)
how can you only have 3 bags left!!! there should be 6 bags left after 4 days if he picks one out each day!! surely
yeah i just rounded it

so yeah 2 singles and 4 doubles = 1/3
11. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by amg_22)
yeah i just rounded it

so yeah 2 singles and 4 doubles = 1/3
yeh decent
12. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by Reminisce)
Graph one, got 1500 then 1450 as optimum profit.

0.6 for final probability

14min,2 people, 5.5 (exclude 10 I believe),

If buns go in one at a time its 5.5 + 3(10) since you can prepare whilst baking.

Then its 3(5.5) + 10 IF all together.
so basically the exact same as me?? hahaha
13. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by sreddy17)
so basically the exact same as me?? hahaha
Yup, sorry just felt like writing it out
14. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by sreddy17)
Hi guys, I will do an unofficial mark scheme from what I can remember:
1.) draw network, then it was length 8 and a,c,e,g or something can't remember exactly but it had 4 arcs.

2.) relatively straightforward.
- application something to do with differentiation
-root 5 why is it included... not sure.

3.) For this graph theory question I can't remember exactly what I had but for part 2, i had one circle with a circle in it. and i had a little circle just touching the big circle.

4.)X = number of motors of type X made
etc
inequalities: there was one with x>5 and y>5 (greater than or equal to)

and 2 more i cant remember...

the max profit was where the two lines intersected.
for the last part the inequality changed and u just had to plot and give integer values.

5.) probably the hardest question, but bcoz it said 9 bags... u had to reject 9, and assign 0-7 to doubles and 8 to single.

and i got 0.6 as final probability for last question.. i added all my probs up i had 4 (4/6) and one 2/6

6.) 14 minutes was min time, after you draw the network.. and critical activities i can't remember
1 dummy used
took 2 ppl to do it in min time
min time for one just add them all up 5.5 i think( excluding the 10 one h) or 15.5 if u add h on, question didn't really make it that clear.
and then u had to draw a critical network showing the 5.5 then the 10 then he 5.5 again and 10 three times...

CANT REMEMBER MUCH ELSE
Cheers for this buddy,

You have made me feel a lot better (assuming you are correct on most!) as I calibrate with you on most.

I thought it was difficult my views on each question:

1. Easy but I think you had to stop the Dijkstra's after finding the correct option of 8 and not continue to put in the remaining node of 9, as the algorithm dictates this but will only lose 1 mark either way.
2. The actual algorithm wasn't bad though daunting and I was worried with so many figures etc, can't remember the values, didn't really like it. Didn't understand either 1 mark sub question.
3. Quite happy with this one, made sense in my head luckily no problems.
4. LP was traditional, was in a bit of a panic but came back to it and got nice values for all (I used simultaneous equations for the first maximisation when it clearly went through the points on the graph nicely lol). My biggest concern here was my poor handwriting for some poor examiner! Found the integer bit straightforward, not sure why it was 4 marks though! (Maybe because like I said you HAD to demonstrate the simultaneous equation here).
5. Started going downhill here, I remember getting 1/3 for something and think I got most of the marks up until the last 2 2 mark questions. Must have got the wrong end of the stick wasn't sure what was going on, didn't know why the probability was 2 marks anyhow...
6. My biggest worry was the activity network after the exam I got 1 dummy too but real mix of opinions, how sure are you? I got 14 mins etc but just have a feeling I will lose marks and follow through marks because the network was dodgy. Recognise your answers for the following questions, last 1 or 2 calculations I am unsure of.

Overall not great but hopefully have done better than I thought and the examiners will be considerate. (Because using their minimalistic mark schemes they "publish" penalises quite heavily) So hopefully some ECF marks...

Grade boundaries appear to normally high I would like it to be at least lower than 60 but I think I've done well in C1 / C2 so shouldn't have to worry about the overall grade too much!

That's me done for exams now! - Thank's again!
15. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by Alex Bampton)
Cheers for this buddy,

You have made me feel a lot better (assuming you are correct on most!) as I calibrate with you on most.

I thought it was difficult my views on each question:

1. Easy but I think you had to stop the Dijkstra's after finding the correct option of 8 and not continue to put in the remaining node of 9, as the algorithm dictates this but will only lose 1 mark either way.
2. The actual algorithm wasn't bad though daunting and I was worried with so many figures etc, can't remember the values, didn't really like it. Didn't understand either 1 mark sub question.
3. Quite happy with this one, made sense in my head luckily no problems.
4. LP was traditional, was in a bit of a panic but came back to it and got nice values for all (I used simultaneous equations for the first maximisation when it clearly went through the points on the graph nicely lol). My biggest concern here was my poor handwriting for some poor examiner! Found the integer bit straightforward, not sure why it was 4 marks though! (Maybe because like I said you HAD to demonstrate the simultaneous equation here).
5. Started going downhill here, I remember getting 1/3 for something and think I got most of the marks up until the last 2 2 mark questions. Must have got the wrong end of the stick wasn't sure what was going on, didn't know why the probability was 2 marks anyhow...
6. My biggest worry was the activity network after the exam I got 1 dummy too but real mix of opinions, how sure are you? I got 14 mins etc but just have a feeling I will lose marks and follow through marks because the network was dodgy. Recognise your answers for the following questions, last 1 or 2 calculations I am unsure of.

Overall not great but hopefully have done better than I thought and the examiners will be considerate. (Because using their minimalistic mark schemes they "publish" penalises quite heavily) So hopefully some ECF marks...

Grade boundaries appear to normally high I would like it to be at least lower than 60 but I think I've done well in C1 / C2 so shouldn't have to worry about the overall grade too much!

That's me done for exams now! - Thank's again!
It's ok man. and yeah it was just the one dummy 95 percent certain, defo not 3 anyway. just relax man enjoy yourself, all your exams have finished!!!
16. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by It's Jo :))
I got 3 dummies...
Yeah i got 3 dummies. As one of the nodes had 3 precending activities (which would imply 2 dummies and 1 normal arc) and then another one with 2 preceding activities. I think it can be drawn with dummies or normal arcs representing 0 so you should still get full marks if it works.
Last edited by jonny7bell; 31-05-2012 at 14:45.
17. Re: D1 Ocr Mei June 2012 Official Discussion
What did you do for simulation for day 4? I had random numbers for days 2 and 3 and i think i got them right, but how did you get the simulation for day 4?
18. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by jonny7bell)
What did you do for simulation for day 4? I had random numbers for days 2 and 3 and i think i got them right, but how did you get the simulation for day 4?
you had to make new simulations for day 4
19. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by jonny7bell)
Yeah i got 3 dummies. As one of the nodes had 3 precending activities (which would imply 2 dummies and 1 normal arc) and then another one with 2 preceding activities. I think it can be drawn with dummies or normal arcs representing 0 so you should still get full marks if it works.
yes 3 preceding activities doesn't mean 3 dummies. you needed 1 dummy to prevent same i and j activity...
20. Re: D1 Ocr Mei June 2012 Official Discussion
(Original post by jonny7bell)
Yeah i got 3 dummies. As one of the nodes had 3 precending activities (which would imply 2 dummies and 1 normal arc) and then another one with 2 preceding activities. I think it can be drawn with dummies or normal arcs representing 0 so you should still get full marks if it works.
2 preceding activities doesn't mean a dummy... only if two preceding activities and one of them is involved in another one.. which it wasn't. therefore, 1 dummy.

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