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# Mr M's OCR (not OCR MEI) Core 3 answers January 2012 Tweet

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1. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
(Original post by Mr M)
Thanks Mr M for your answers. For Q5 ii) I drew a dotted line of y = x and labelled it, then drew the inverse function as a solid line but stupidly didn't label that, would I get away with it? Also, for iii) I got all the bits in brackets right but instead of multiplying it by 2/3, I multiplied it by 1/6 (again stupid mistakes). As it's a 4 marker rather than a 3, would I lose 2 here or just the 1? For Q8 i) I got as far as but then made errors after this so didn't get it in the required form - would I scrape 1 mark for this? And for Q9 iii) I proceeded to find the co-ordinates of the max. point of -f(x) and my y coordinate was -4k, and so subsequently I initally got k = -5, and then said it was k = 5 because I wanted value for |f(x)|, then formed a quadratic but didn't bother to use the quadratic formula and just plugged them into my calculator's equation solver to get the two solutions , so my final answer was the three required as I already found the x coordinate of the max point. But actually I've checked through and realised that it was just a silly error and in fact my answer should have been k = 5 and not k = -5. Will they notice I fudged my k value a bit?
Last edited by Ivo; 21-01-2012 at 14:11.
2. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
Any one think this exam was harder than june 2011... or about the same?? Let me know please!
3. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
(Original post by Ivo)
Thanks Mr M for your answers. For Q5 ii) I drew a dotted line of y = x and labelled it, then drew the inverse function as a solid line but stupidly didn't label that, would I get away with it? Also, for iii) I got all the bits in brackets right but instead of multiplying it by 2/3, I multiplied it by 1/6 (again stupid mistakes). As it's a 4 marker rather than a 3, would I lose 2 here or just the 1? For Q8 i) I got as far as but then made errors after this so didn't get it in the required form - would I scrape 1 mark for this? And for Q9 iii) I proceeded to find the co-ordinates of the max. point of -f(x) and my y coordinate was -4k, and so subsequently I initally got k = -5, and then said it was k = 5 because I wanted value for |f(x)|, then formed a quadratic but didn't bother to use the quadratic formula and just plugged them into my calculator's equation solver to get the two solutions , so my final answer was the three required as I already found the x coordinate of the max point. But actually I've checked through and realised that it was just a silly error and in fact my answer should have been k = 5 and not k = -5. Will they notice I fudged my k value a bit?
Q5 prob ok for the graph

lose 2 next bit I think

1 mark for Q8.

they *might* not notice your fudge
4. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
(Original post by Mr M)
Ah OK thank you! Just out of interest, if they notice the fudge do they not credit anything further? Also, for the iterations I showed working for the first iterate, and then didn't bother and just wrote down a few more values. Would that be OK?
5. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
(Original post by Ivo)
Ah OK thank you! Just out of interest, if they notice the fudge do they not credit anything further? Also, for the iterations I showed working for the first iterate, and then didn't bother and just wrote down a few more values. Would that be OK?
They should read it all. So long as you listed your iterations that is fine.
6. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
[QUOTE=Mr M;35974285]Mr M's OCR (not OCR MEI) Core 3 answers January 2012
8. i)

k = 8 (3 marks)

ii) (2 marks)

iii) 2 and -2/3 (5 marks)

How did u get in the question it said pi/24 which when put into cos 4\theta gives square root three over 2.
7. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
(Original post by minip12qss)
How did u get in the question it said pi/24 which when put into cos 4\theta gives square root three over 2.
8. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
(Original post by Mr M)
So how many marks would i have dropped for leaving it as the square root of three over 2 btw what was the question
9. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
(Original post by minip12qss)
So how many marks would i have dropped for leaving it as the square root of three over 2 btw what was the question
One mark if you are lucky.
10. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
For the rate of decrease Q7b, would I lose a mark if I wrote -2.73 grams per year?
Thanks!
11. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
(Original post by Mr M)
Wow that was convulted! You might be ok as you rejected the invalid solutions in the end.
Yeah I forgot about drawing the graph!

I circled my answer "k=5" if that helps? And I put arrows saying "answer here" lol
12. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
Did question 6i not ask for dx/dy rather than dy/dx?
Secondly, stupidly I forgot to put the dx after some of my integrals. Is this something I'm likely to lose more than one mark for?
13. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
how many marks do you think I will lose if I left the final answer in decimal form, not exact form?
14. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
hi!! thanks for sticking this up Mr M!

For question 3; i think i i had 9x + y - 10 and 2/3 =0 would i still get full marks?

and what was question 8 part iii?
15. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
(Original post by Smiley Face :))
Any one think this exam was harder than june 2011... or about the same?? Let me know please!
i think this one was harder than june 2011 - but maybe thats because i did this one in exam conditions under pressure.

but june 2011 was much harder than other past papers!
16. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
yay i think i might actually have done well somehow

there arent any answers there that seem different from what i put (based upon my vague recollection of how i answered), but there are bound to be a few slips here and there. any idea what the grade boundaries are like in terms of raw marks?
17. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
What was question 5(i) again? I cant remember :/
Oh, and also, would I get any marks for getting K=4 on question 8?
18. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
(Original post by s04582)
What was question 5(i) again? I cant remember :/
Oh, and also, would I get any marks for getting K=4 on question 8?
5i) State: ff(26); f^-1(8)
19. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
(Original post by Akash2611)
For the rate of decrease Q7b, would I lose a mark if I wrote -2.73 grams per year?
Thanks!
I thnk that mistake will be condoned.
20. Re: Mr M's OCR (not OCR MEI) Core 3 answers January 2012
(Original post by ALevelGirl)
hi!! thanks for sticking this up Mr M!

For question 3; i think i i had 9x + y - 10 and 2/3 =0 would i still get full marks?

and what was question 8 part iii?
drop 1 mark for 3

8partiii was about finding the greatest and least values of a trigonometric expression
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