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OCR (not OCR MEI) Core 1 Answers Jan 2011

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Reply 60
Original post by WildBerry
I think 90 is 64 , as 64/72 is around 89% , so with ums it might be higher :confused:


That's quite good, I think I will have lost 7 absolute maximum so hopefully I still get 90 UMS! :P It seemed like quite a hard paper compared to some I've seen so the grade boundaries might be lower? :L
Thanks so much for this!
Also, what will the grade boundaries be like?
Reply 63
could any1 do the working out for the last question please(Mr.M).
Reply 64
Because I put the answers for 9.)iv.) in the part iii.) box, and part iii.) in the part ii.) box as a result of skipping the y=k tangent question, do you think those questions (they were answered correctly) will be marked? I feel like an idiot for it, and in part didn't see the 9.)iv.) box on the back of the paper.
Reply 65
can i just ask why for 8iv it's x<3 rather than something like -1<x<6 (can't quite remember the question). wasn't it 6-5x-x^2>0? surely that would go to (x-1)(x+6)<0 and then to -1<x<6. sorry if i've got the the question slightly wrong!
Original post by Konshi
Holy **** I've completely ****ed up the paper


QFT.

I panicked. I've never been like that in an exam but I completely froze up for about 20 minutes in the middle. I couldn't answer the chord question because my mind went blank. I even know how to do it, I just panicked.

Now I can't remember if I got k=-9 or not. I know I got a negative number but I'm not sure what. I got 16k+144=0 though. Or did I? I'm seriously panicking now and I really shouldn't be. :frown:

Ah well, there's always the resits.
Reply 67
Original post by JEDWARD
can i just ask why for 8iv it's x<3 rather than something like -1<x<6 (can't quite remember the question). wasn't it 6-5x-x^2>0? surely that would go to (x-1)(x+6)<0 and then to -1<x<6. sorry if i've got the the question slightly wrong!


It is "X<3" because the graph equation was "y = 7+6x-x^2"
Therefore it factorised to -[(x + 7)(x - 1)]
Thus Line of symmetry is x = 3
Thus increasing function is x<3 as it is an upside down parabola

I'm so annoyed I've dropped 1 mark!! That should be 100 UMS though?? I lost it on k = -9 for the discrimanant equal roots bit... I put k = 9 .... forgot the negative -.- GAH

I found it the most difficult paper to date though to be honest, definitely required much more thinking and application of knowledge in like the circle questions!! Boundaries must be lower!!
Reply 68
Oh ok! thanks a lot.
Reply 69
Original post by The Joker666 x

Original post by The Joker666 x
Isn't the answer to 7iii? 9 (not -9). This was the one where the discriminant equaled 0 and you had to find k.


no it is -9. as it was -k so -(-9) is 9. if you know what i mean. i put down 9 first in the exam then rechecked it and its definately -9 :smile:
Reply 70
Guys how many marks do u think I will get for question 5)(ii) ? I put down y = (-x-3)^3... but the actual answer was -(x-3)^3 and the question was out of 2 marks. And thats the only question I got wrong so how many UMS do you think I will get ? :s-smilie:
Reply 71
Also does anyone have the question paper to post?
Reply 72
Original post by merrmerr
Whattt??? I swear question 6 you had to differentiate 1/4x
So wouldnt that be (4x)^-1
so then it would be -1/4x^2??


My textbook actually had a section on this calling it the common mistake.

Unparseable latex formula:

\frac {1}{4x} = \frac {1}{4}X^-^1

as the time four is for the denominator and not the numerator.
Reply 73
Original post by kafeelmirza
hey mr m please could you tell me firstly. What was question 3) iii) and also please also for 6 i) i remember seeing. 1/4x as one of the figures to differentiate is it ok if i put (4x)^-1 because it was 1/4x so it means the whole 4x is to the power of -1? thank you


I agree, i think 6 i was 1/4x, or -1/4x, so I think you're right with the (4x)^-1!:smile:
Reply 74
Original post by zenmore

Original post by zenmore
Guys how many marks do u think I will get for question 5)(ii) ? I put down y = (-x-3)^3... but the actual answer was -(x-3)^3 and the question was out of 2 marks. And thats the only question I got wrong so how many UMS do you think I will get ? :s-smilie:


hi. you'll probs get one mark for geting the -3 bit. and overall if you think you've only lost one mark then im guessin its about 97/98 UMS? not sure tho.
Reply 75
4x^-1 = 4 . x^-1

bodmas
Reply 76
by the way... how many people messed up question 2, I know that at least 10 people in my class expanded the brackets and got the wrong answer!
Original post by Mr M
OCR (not OCR MEI) Core 1 Answers Jan 2011


1. (i) Length of AB = 10 (2 marks)

(ii) Gradient of AB = -3/4 (2 marks)

(iii) They are perpendicular (3 marks)


2. p = 2 and q = 5 (3 marks)


3. (i) 8128^{\frac{1}{2}} (1 mark)

(ii) 828^{-2} (1 mark)

(iii) 8838^{\frac{8}{3}} (3 marks)


4. x=13,0,43,1x = \frac{1}{3}, 0, \frac{4}{3}, 1 (6 marks)


5. (i) Sketch of y=x3y=-x^3 (2 marks)

(ii) y=(x3)3y = -(x-3)^3 (2 marks)

(iii) Stretch scale factor 5 in y direction OR stretch scale factor 5135^{-\frac{1}{3}} in x direction (2 marks)


6. (i) 10x3+x24+1-10x^{-3} + \frac{x^{-2}}{4} + 1 (4 marks)

(ii) 30x4x3230x^{-4} - \frac{x^{-3}}{2} (2 marks)


7. (i) 4(x+32)2124 (x + \frac{3}{2})^2 - 12 (4 marks)

(ii) x=32±3x = \frac{-3}{2} \pm \sqrt 3 (4 marks)

(iii) k = -9 (3 marks)


8. (i) 4x + y - 32 = 0 (6 marks)

(ii) Midpoint = (6.5, 6) (3 marks)

(iii) x = 3 (2 marks)

(iv) x3x \leq 3 or x<3x < 3 (2 marks)


9. (i) Centre (4, 1) radius 252 \sqrt{5} (3 marks)

(ii) y=1±25y = 1 \pm 2 \sqrt 5 (3 marks)

(iii) Length of chord = 8 (3 marks)

(iv) (6, -3) (6 marks)


Mr M do you have the answers to the Mechanics 2 OCR paper today please?
Original post by Contrad!ction.
QFT.

I panicked. I've never been like that in an exam but I completely froze up for about 20 minutes in the middle. I couldn't answer the chord question because my mind went blank. I even know how to do it, I just panicked.

Now I can't remember if I got k=-9 or not. I know I got a negative number but I'm not sure what. I got 16k+144=0 though. Or did I? I'm seriously panicking now and I really shouldn't be. :frown:

Ah well, there's always the resits.


k= -9 & it is worked out using the discriminant which will give you 16k + 144 = 0. Then pretty much solve the equation to get k = -9.
(edited 13 years ago)
Reply 79
Original post by tateco
That's quite good, I think I will have lost 7 absolute maximum so hopefully I still get 90 UMS! :P It seemed like quite a hard paper compared to some I've seen so the grade boundaries might be lower? :L


definitely hardest paper so far... you'll probably only need something like 62/63 rather than 65:smile:

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