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# Edexcel C4 June 2016 - Unofficial Markscheme watch

1. (Original post by lfcrules)
Hey gus for the differential equation qiestion , I left it in terms of ln , how many marks do you think ill lose . Also do you think ill lose a marl for not cancelling 8pi/6 to 4pi/3
You'll lose the final A1 mark and possibly a M1 mark depending on what stage your equation in ln was - did you use log rules to end up with ln something or did you just leave it less simplified ?

The other mark will depend on whether the question specified to give the answer in its simplified form - if so then you'll lose another A1 mark.

So you're looking at around 3 marks lost here .
2. (Original post by fefssdf)
For question 4 when you say the wrong time this will depend whether you calculated the time correct in hours but didn't convert to minutes - in which case you'd lose the final A1 mark.

For question 7 for the integral you'll likely use 2 marks for this- M1 mark for calculating the volume, and the A1 mark for getting the incorrect volume. You may lose a further mark depending on how many marks this question was worth, and if your final answer was incorrect then your may have made another error in your method ?

I'd say to be safe you've lost 5-6 marks here.
I think Q4 after the show that I made an error leading to an incorrect answer, and Q7 I integrated both of my integrals with the same limits which followed through, does that change anything? And yeah I reckon 5 or 6 which I will grab with both hands.
3. I think the marks went as follows:

1. A) 6

2. A) 1 B) 3 C) 5

3. A) 5 B) 4

4. A) 4 B) 3

5. A) 4 B) 3

6. A) 6 B) 4 C) 5

7. A) 2 B) 1 C) 4

8. A) 1 B) 2 C) 2 D) 3 E) 2 F) 5

(Correct me if i'm wrong)
4. (Original post by pentsr)
Wud a 69 in c3 nd a 66 in c4 be an A*?
I'd say yes as c3 boundary is low for the A* so you're get a few marks over it; and for c4 you'll probably miss the 90s by a few marks so I think it will average out and you'll get it - I really hope you do !
5. (Original post by Asurat)
I think Q4 after the show that I made an error leading to an incorrect answer, and Q7 I integrated both of my integrals with the same limits which followed through, does that change anything? And yeah I reckon 5 or 6 which I will grab with both hands.
If you've integrated with incorrect limits then you'll get some method marks but not all of them and will lose the answer marks and the final answer mark so yeh you may lose more than 5/6 but I hope you don't
6. (Original post by fefssdf)
You'll lose the final A1 mark and possibly a M1 mark depending on what stage your equation in ln was - did you use log rules to end up with ln something or did you just leave it less simplified ?

The other mark will depend on whether the question specified to give the answer in its simplified form - if so then you'll lose another A1 mark.

So you're looking at around 3 marks lost here .
For the differential equation I ended up with 5t=ln (3600/x^2) which I know is a correct expression as I got part b for that right. Does this make a difference ? if the other question had said exact form , woukd I still lose a mark ?
7. (Original post by lfcrules)
For the differential equation I ended up with 5t=ln (3600/x^2) which I know is a correct expression as I got part b for that right. Does this make a difference ? if the other question had said exact form , woukd I still lose a mark ?
If it's equivalent then you'll get the marks but ' exact form ' typically means in terms of pi/ surds so you'll lose them im nafriad
8. For Q7 I didn't use the volume of a cylinder or whatever, I just integrated to find the area under the y=8 curve and then subtracted the area under the other curve. Does that give the same answer? I can't remember my answer haha but I definitely remember it was 544pi subtract something.
9. (Original post by speed1✈️✈️)
You're looking at a mid to high B, seeing as the grade boundaries WILL skyrocket. An A will be 68/69.
I hope it's not 68. I can see them going up a fair bit, I just hope that people have made enough mistakes for an A to be 66 or 67 max.
10. (Original post by fefssdf)
I'd say yes as c3 boundary is low for the A* so you're get a few marks over it; and for c4 you'll probably miss the 90s by a few marks so I think it will average out and you'll get it - I really hope you do !
Thanks! Hope you do good too !
11. (Original post by fefssdf)
If it's equivalent then you'll get the marks but ' exact form ' typically means in terms of pi/ surds so you'll lose them im nafriad
Thanks for your input , I did have it in pi surd form . The simplified answer was 4pi/3 -root3 whilst I left it as 8pi/6 -root 3.
Thanks again for ur help
12. hey, for q4b, i did exactly waht you did but forgot to convert to minutes so I got up to 0.439 days, would the method marks be 1 or 2 here?
13. (Original post by boyyo)
hey, for q4b, i did exactly waht you did but forgot to convert to minutes so I got up to 0.439 days, would the method marks be 1 or 2 here?
Id have thaught definately two , there cant be more than one mark for converting to minutes
14. Hey for the differential equation question I showed one method for part a and b and then 5 mins before the exam finished I went back and worked it out correctly under the other working out but forgot to cross out the incorrect method.
Will I still get the marks?
15. (Original post by thxmas7)
depends what you got in c1 c2 and the 2 other modulus
Well I think I've done enough to get an A grade overall. C1 was average, i think 68/75, C2 was hopefully 73/75 and I think i got 75/75 for M1 (which makes up for the 68 UMS in S1 last year).
Discounting any method marks I got 66/75 in C3. So yeah, I somehow completely forgot to spot the integral sign or something before the fraction in question 6. I expanded it correctly but didn't proceed any further. It was worth 6 marks though so maybe i got 2. Maths is the only A* I'm hoping for because edexcel unit 4 chemistry completely screwed me over lol
16. For question 4, did they ask you to simplify the equation i wrote x=e^(-5/2)+ln(60)
17. Do you think I could get an A or A* with these?
C1-85, C2-90, S1-98
C3 (predicted): 70 raw, C4 (predicted): 65 raw, D1(predicted): 58 raw
18. (Original post by Tan455)
Hey for the differential equation question I showed one method for part a and b and then 5 mins before the exam finished I went back and worked it out correctly under the other working out but forgot to cross out the incorrect method.
Will I still get the marks?
In some other subjects such as chemistry they apply a list principle, but I doubt they would do that in maths if you ended up arriving at a correct answer.
19. ,,
20. do you reckon 66 in c3 and 68 in C4 to be an A*?

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