OCR (Not MEI) Core 2 Discussion Thread 17th May 2013 + Jan 13 Paper and MS

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I got 37/30, though I don't know anyone else who did

This exam went amazingly well for me after a pretty shoddy c1 on Monday! I wrote down my answers on a scrap bit of paper so il post them up in a while.

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Reply 82

Music99

Original post by Ellie_Rosa

I got 37/30, though I don't know anyone else who did

that's correct.

Reply 83

Goods

C2.

1)6.39

2)i)106.3,253.7
ii) 71.6, 251.6

3) 64 + 960x +6000x^2
ii) c=-11

4) 4/5x^4 -3x^2 + x + c
ii) -12x^-2 +c
iii)a=2

5i)62.2
ii)34.0

6)i)963
ii) n=<17.2 therefore greatest n=17

7i) shown
ii)37/30

8)y=1 , y=4
ii) interger then fraction
iii) shown

9)i) 15
ii)x=-1/2, x=-1, x=3/2
iii) x= 2/3pi, pi, 4/3pi

i THINK that's all correct

Reply 84

Hannburger

Logs 'show that' (question 8), I did: 7 'show that' question:
y=y
a^x=4b^x
log2(a^x)=log2(4)+log2(b^x)
x(log2(a)-log2(b)=2
ab=2 therefore b=2/a, sub this in to get
x(log2(a)-log2(2/a))=2
x(log2(a)-(log2(2)-log2(a))=2
x(log2(a)-1+log2(a))=2
x(2log2(a)-a)=2
Therefore x= 2/(2log2(a)-1)
Hope this helps! (:

Reply 85

Hannburger

Original post by Goods

Hi, I got all of them, but on 9ii, you were only meant to factorise completley, not find the solutions too (: Can you remember what question 5 is??

Reply 86

niaphonic

Original post by _JC95

I tried to do the tangent area under the graph question 2 ways...

First I got 37/30 by subtracting the area of the right angled triangle.

Then, to check, i tried integrating. (x^3/2 - 1) - (3x-5) and got a completely different answer of 1.9

Surely both methods are valid and should both produce the exact same answer??

In the end I stuck with the original 37/30, the rest of the paper was pretty fair.

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In theory both methods are valid, but when you integrate (x^3/2 - 1) - (3x-5) using the limits x=4 and x=1, the area between the tangent (y=3x-5) and the x-axis includes a little chunk below the x-axis within these limits.
That's why you get a different answer to integrating separately and using the limits x=4 and x=1 for (x^3/2 - 1), and x=4 and x=5/3 for (3x-5), then subtracting one from the other.

(edited 10 years ago)

Reply 87

Goods

Original post by Hannburger

Hi, I got all of them, but on 9ii, you were only meant to factorise completley, not find the solutions too (: Can you remember what question 5 is??

Ehh had to factories to solve so ill get them :smile:

It was a arc of 0.8 rad radius 16 minus a triangle with a side as the radius and a side of 7. Find area then perimeter of arc minus the triangle

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Reply 88

_JC95

Original post by stefanconstant

Well 37/30
is the right answer so you're fine..
Did you integrate it right?

I believe so:s have a go?

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Reply 89

Hannburger

Original post by Goods

Ehh had to factories to solve so ill get them :smile:

It was a arc of 0.8 rad radius 16 minus a triangle with a side as the radius and a side of 7. Find area then perimeter of arc minus the triangle

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Ah yeah, thanks, got those answers too yey! (:

Reply 90

stefanconstant

Original post by _JC95

I believe so:s have a go?

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Integrated is 2/5x^5/2 -3/2x^2 +4x?

Reply 91

DingDong!

Did anyone else find the equation of the tangent and theb integrate between the two points and take that from the area under the curve?? Everyone seems to have used a triangle

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Reply 92

geekD96

wat was question 2 van someone tell me... please thanks

Reply 93

_JC95

Original post by stefanconstant

Integrated is 2/5x^5/2 -3/2x^2 +4x?

yeah...

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Reply 94

stefanconstant

Original post by _JC95

yeah...

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yeah I got 1.9 too lol...
I put 37/30
they should both be the same unless we're missing something

Reply 95

kiraeil

What do people think roughly grade boundary will be for an A?
Also for the area under curve question would I get some marks for workings as i worked out equation of tangent and area of small triangle but got complete wrong answer?
thanks :smile:

57? (80% of 72)

Answers to Summer paper are here:

http://www.thestudentroom.co.uk/showthread.php?t=2354368

I'll be answering questions in a while.

Reply 98

kiraeil

What were people's working for 5ii) the question on finding the perimeter?

Reply 99

Urgelt

On the last part of the last question, I made a silly mistake. I got 2 of the 3 required answered correct, but then ended up with another 2 obviously wrong answers (I don't know what the hell I was thinking, but I put it down to rushing the last question, as I had skipped question 5 and wanted to get back to it). How many marks (out of 4) could I expect to drop for this mistake? I was thinking 1 or 2, but I don't know. I'm kicking myself, because it was probably one of the easiest questions on the paper.
Another thing, some people have been telling me that the UMS at AS level isn't particularly significant, which becomes more important at A2. For instance, to get an A* overall, you need an average of 90UMS at A2, and an average of 80UMS or more across AS and A2. This would mean that if you got an avrg of 90UMS at A2, 70UMS at AS would suffice to get the A* (90+70=160/2=80). What are your thoughts on this?