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# OCR MEI C3 Maths June 2015 watch

1. How many marks was question 5 ? Specifically for finding the derivative?

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2. In the integration in Q8 where you had to do the area of the rectangle - the area under the graph, was the area of the rectangle 3(units^2)?
3. (Original post by WaiKon1337)
In the integration in Q8 where you had to do the area of the rectangle - the area under the graph, was the area of the rectangle 3(units^2)?
Yeah it was, area between x=1 x=4 y=1 and y=0 3*1=3
4. (Original post by 123BOBBY)
arcsinx=arccosx --> tanx=1 -->x=pie/4
5. guys for volume ques; if i put r = hsin 45 (stupid me :/ ) and done it but i got a differnet dV/dr would i get any follow through marks? also would you get a mark just writing dV/dt or something = 5 ?
6. (Original post by RemainSilent)
guys for volume ques; if i put r = hsin 45 (stupid me :/ ) and done it but i got a differnet dV/dr would i get any follow through marks? also would you get a mark just writing dV/dt or something = 5 ?
Perhaps 1 mark for writing dV/dt = 5 (PERHAPS).
I would have thought you will lose 2 marks for putting r = hsin45 (one for the straight mistake, and one for the answer mark that followed for dV/dh).

Not sure though - 2 or 3 out of 5.
7. is someone able to draw the graph please think mines wrong
8. (Original post by RemainSilent)
is someone able to draw the graph please think mines wrong
http://www.wolframalpha.com/input/?i...5E0.5+%2B+2%29
9. (Original post by SH0405)
set each side of the equation equal to theta (an angle)
rearrange to obtain x in terms of theta
divide through to obtain expression in terms of theta
work out theta
work out x using one of the 'x in terms of theta' equations
10. (Original post by Primus2x)
How many marks was question 5 ? Specifically for finding the derivative?

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I think finding the derivative is worth 3 marks. 1 mark for verifying (1, 1) and 1 mark for substituting in (1, 1) and obtaining the correct answer.

Another alternative is 1 for verify. 2 for derivative (both method). 1 method for subbing in (1, 1). 1 accuracy for answer = 1/2
11. (Original post by Duskstar)
set each side of the equation equal to theta (an angle)
rearrange to obtain x in terms of theta
divide through to obtain expression in terms of theta
work out theta
work out x using one of the 'x in terms of theta' equations
I swear I didn't quote you...your working's fine .
12. (Original post by SH0405)
I swear I didn't quote you...your working's fine .
Oh I thought you just wanted to know how they did it lol. And they didn't do it correctly anyway, but those steps are how you get the tan bit ~ thanks
13. (Original post by Duskstar)
Oh I thought you just wanted to know how they did it lol. And they didn't do it correctly anyway, but those steps are how you get the tan bit ~ thanks
Yes, it was a questioning approach; 'can you show me your working (which I know is wrong...)?'
14. How many marks do you think you got today?
15. (Original post by Duskstar)
You probably lost 2 marks for not doing the rectangle, and then 2 marks for the g(x) question, because the intention was to literally write down you answer before * -1. On the sketch question you probably lost 1 or 2 marks on the actual sketch (out of 2) depending what qualities it had of what it was supposed to be.
Thanks, that makes me feel better. Bring on C4.
16. In Q 9 when you have to find the area enclosed by the curve (the bit under the x axis) and by integrating from 0 to ln3, you got 3ln3-4 or something. This gets a negative value as its under the x axis, but surely an area must be positive so it should be 4-3ln3?
17. (Original post by 123BOBBY)
wasnt there an asymptote at x=3
No
18. (Original post by Duskstar)
I'm going to try and do a mark scheme here. Bare in mind that I'm in Year 12 too >.>

Firstly, thanks to Barrel who actually posted the paper (page 15). here are the pages in order:
http://www.thestudentroom.co.uk/atta...9&d=1434104177
http://www.thestudentroom.co.uk/atta...1&d=1434104202
http://www.thestudentroom.co.uk/atta...3&d=1434104269
http://www.thestudentroom.co.uk/atta...5&d=1434104300

- I wasn't completely sure of the method for the second part, this is what a friend told me the method was (I think I do it correctly). Because of the nature of these two questions, however, I'm not 100% sure you need a method if you get the answer correct. It's only 1 mark each either way ~

Anything I missed or got wrong just ask. If you think it would be marked differently then say so too.
Didn't do this exam (I do edexcel), but I like snooping on other papers. Here's how I would do 6b)

Arcsin(x))=arccos(x)

Cos(arcsin(x))=x

Sin(90-arcsin(x))=x

90-arcsin(x)=arcsin(x)

Then solve for x like this
19. (Original post by Gome44)
Didn't do this exam (I do edexcel), but I like snooping on other papers. Here's how I would do 6b)

Arcsin(x))=arccos(x)

Cos(arcsin(x))=x

Sin(90-arcsin(x))=x

90-arcsin(x)=arcsin(x)

Then solve for x like this
Neat
20. (Original post by Duskstar)
Neat
Your papers look so much harder than ours

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