OCR C4 (not mei) 18th June 2013 revision

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This is effectively a preliminary markscheme until Mr M posts his full definitive solutions. Some of my answers may be wrong. Spoilered incase you don't want to see them :smile:

Spoiler

Great, I agree with you on all of them :-) Although, I couldn't do 10i or 10ii (the proof part), but I spotted what they were getting at for 10iii so grabbed the marks there :P The volume of the pyramid was 9.33 I believe (to 3sf)

(edited 10 years ago)

Reply 481

Maid Marian

Original post by SJ12345

I got 8.68

That was the first answer I got but I scribbled it out because I thought it was too low :facepalm:

Reply 482

Vip3rgt9

Original post by ActaNonVerba

I can see grade boundaries dropping to about 50 for an A (52 is the lowest it's ever dropped)

I agree and I thought that this paper was as hard or harder than that paper.

Reply 483

bellaanne

THAT EXAM COULDN'T HAVE GONE ANY WORSE
WHY OCR? WHY
the exam was so long I couldn't even think for long enough without thinking I'm not going to have time to do the other questions
:frown:

Reply 484

a10

Original post by eggfriedrice

Isnt it slightly unfair people can plot the graphs using theirs calculators during the exam? :| "pay £80 and get a slight advantage. " Meh.

I totally agree with this....

Reply 485

samthegooner

I got 180-171.3= 8.67 degrees for angle.
Mucked up on tan2x.
Didn't have a clue on later parts of Q10.
Can't certainly say any answer looks convincing.

Reply 486

a10

can someone confirm this:

for the tan question my final integral was

-2ln(2- sec^2(x))

and I subbed in values wrong for the first part so I ended up with

(-2 ln 2/3) + 2ln(-6+4root 3)

can someone confirm whether they got the -6+4 root 3 part?

Reply 487

louise_234

Original post by Maid Marian

That's what I did, but apparently it's not right and I didn't think it could be right either because it was worth 5 marks :s-smilie:

you can change it to sin2x/cos2x

Reply 488

C94

Just fml, its all over.

Reply 489

Maid Marian

Did anyone else not have a clue what q10 was trying to get at?

I got the first part, but the rest of it :lolwut:

Reply 490

JoshL123

Did anyone get t= -1? Fml :/

Reply 491

SexyAndIKnowIt.

I think the first half of the exam was lovely. The second half though *kill me*

Reply 492

printergirl

Original post by JoshL123

Did anyone get t= -1? Fml :/

i did

but i can tell you now we're wrong

Reply 493

Maid Marian

Original post by louise_234

you can change it to sin2x/cos2x

Would that have worked? Worst thing is, I'd written some identities on the post it note with my desk number on it, and just as I gave the lady the paper I noticed them and I realised that's what I should have done :frown:

Reply 494

Theo115

Original post by Benjy100

This is effectively a preliminary markscheme until Mr M posts his full definitive solutions. Some of my answers may be wrong. Spoilered incase you don't want to see them :smile:

Spoiler

Ben, I do not agree with your answer for the angle BAC because you had to find the angle between the vector BA and the vector AC. I believe what you did was find the angle between AB and AC which is incorrect. I got the same answer as you but did 180-ans, to achieve an answer of 8.68 degrees. I am so annoyed though because I messed up on the differential equation and consequently the question after about the volume. Hopefully I will get error carried forward. Hopefully.

Reply 495

SJ12345

Did anyone get 0.136 on any part of question 10?

Reply 496

JoshL123

Original post by printergirl

i did

but i can tell you now we're wrong

Oh man :/

Reply 497

Theo115

Original post by Maid Marian

That's what I did, but apparently it's not right and I didn't think it could be right either because it was worth 5 marks :s-smilie:

It is just 0.5ln(sec2x).

Reply 498

h2shin

Original post by SJ12345

Did anyone get 0.136 on any part of question 10?

That was the approximation yeah :smile:

Reply 499

username970812

Original post by Benjy100

This is effectively a preliminary markscheme until Mr M posts his full definitive solutions. Some of my answers may be wrong. Spoilered incase you don't want to see them :smile:

Spoiler

Thanks for the MS

For #3 how did you show they are not parallel? I just stated they are not factors