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Mr M's OCR (not OCR MEI) Core 3 Answers June 2012

Mr M's OCR (not OCR MEI) Core 3 Answers June 2012


1. x<43x<\frac{4}{3} and x>6x>6 (5 marks)


2. (i) Show 261 (3 marks)

(ii) 361 (3 marks)


3. (i) Show tan theta = 6 (3 marks)

(ii) (a) 57\frac{5}{7} (2 marks)

(b) 1235-\frac{12}{35} (2 marks)


4. (a) Show integral = 24 (4 marks)

(b) e2+8e12\frac{e^2+8e-1}{2} (4 marks)


5. (i) Show one real root (3 marks)

(ii) (a) 3 and 4 (3 marks)

(b) 3.24 (4 marks)


6. (i) 12.17 (4 marks)

(ii) 0.183 cubic metres per hour (3 marks)


7. a = 4 and x = -0.5 (7 marks)


8. (i) 5sin(θ+53.1301)5 \sin (\theta + 53.1301) (3 marks)

(ii) (a) -64.7 degs and 138 degs (4 marks)

(b) k = 8 and c = 3 (4 marks)


9. (i) Show derivative (3 marks)

(ii) π(3e4+1)2\frac{\pi (3e^4 + 1)}{2} (6 marks)

(iii) π(e41)2\frac{\pi (e^4 -1)}{2} (2 marks)
(edited 11 years ago)

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Reply 1
thanks again!
Reply 2
Thanks :smile:
Reply 3
Mr M, for question 9(ii) for some reason I differentiated ln(2y) instead of integrating (I was trying to integrate but I was just being retarded), and got my answer from there. Will I get a mark?

EDIT: Btw thanks a lot for the solutions! :smile:
Reply 4
Mr M 4(b) I accidently messed up when multiplying out the brackets but integrated the terms are everything fine - how many marks would I get for that? :smile:

hope the after school meeting was...fun? :tongue:
Reply 5
Oh and would it be okay for 4(b) to give my answer as e(0.5e+4)-0.5? Thanks
Original post by tahseen1995
Mr M, for question 9(ii) for some reason I differentiated ln(2y) instead of integrating (I was trying to integrate but I was just being retarded), and got my answer from there. Will I get a mark?

EDIT: Btw thanks a lot for the solutions! :smile:


I can't say from what you have told me - it doesn't sound hopeful!
Reply 7
How many marks would I drop if I put 4/3 < x < 6 for q1
, and for using g^1(x) instead of g(x) for the second part of 7?
Original post by tahseen1995
Oh and would it be okay for 4(b) to give my answer as e(0.5e+4)-0.5? Thanks


yes
Reply 9
Original post by Mr M
Mr M's OCR (not OCR MEI) Core 3 Answers June 2012


Mr. M, for 9ii) (the 6 mark question), I did everything correctly up till the point where we had to calculate the lower bound. For some reason, because i'm a dog I differentiated rather than just plugging x=0 into f(x), hence I integrated with lower bound 1, instead of lower bound 1/2. All the steps in the integration were correct, but my final answer would be wrong since the lower limit I subbed in was wrong. How many marks would I lose in your opinion?
Original post by Doctor.
Mr M 4(b) I accidently messed up when multiplying out the brackets but integrated the terms are everything fine - how many marks would I get for that? :smile:

hope the after school meeting was...fun? :tongue:


It was mercifully brief. I did maths and pretended to listen.

probably 2 marks
I can't remember what I put for 4b, can anyone remember the question? Thanks.
Original post by Tukazoar
How many marks would I drop if I put 4/3 < x < 6 for q1
, and for using g^1(x) instead of g(x) for the second part of 7?


drop 1 mark and drop 3 marks probably
Original post by Mr M
I can't say from what you have told me - it doesn't sound hopeful!


What I meant is I correctly rearranged the equation to get pi times the integral of y=ln(2x) with limits of 1/2e^(4) and 1/2, but instead of using part (i) of question 9 to find the integral of ln(2x) I integrated ln(2x) to 1/x (I panicked due to lack of time) and went from there.

I was wondering if would at least get a mark for correctly rearranging the equation and realising the the area of the shaded region rotated about the y axis would be the integral of ln(2x) within limits of 1/2e^(4) and 1/2 multiplied by pi.

...did I make sense?

lol thank you
(edited 11 years ago)
I'm off home now but will answer some more questions later (in about one hour).
Original post by Doctor.
Mr M 4(b) I accidently messed up when multiplying out the brackets but integrated the terms are everything fine - how many marks would I get for that? :smile:

hope the after school meeting was...fun? :tongue:



Original post by tahseen1995
Mr M, for question 9(ii) for some reason I differentiated ln(2y) instead of integrating (I was trying to integrate but I was just being retarded), and got my answer from there. Will I get a mark?

EDIT: Btw thanks a lot for the solutions! :smile:


Is this your actual teacher? Seems a bit weird :smile: but I suppose it's a good idea too.
for 4b i put e^x2 and not 2x. hw much wud i lose and for the last i intergraded put the the y values. ie e^4 one in but got soma dfferent. like 2pi e^4. i also integrated the line and wrkd that out?
Reply 17
Original post by Junaid96
Is this your actual teacher? Seems a bit weird :smile: but I suppose it's a good idea too.


Maybe :ninja:

Just kidding, nope but I do casually stalk Mr M :colonhash: (Only on TSR lol) would be so weird if someone did that in real life :lol:
Reply 18
How many marks would I lose for getting

k = 3/5
c = 40

Because I read the question as 37 not MINUS 37!
Original post by Mr M
Mr M's OCR (not OCR MEI) Core 3 Answers June 2012




Thanks. Just two questions.

On question 9iii) if I used my answer from question 9ii) to calculate the volume (but followed the correct method) would I get any of the 2 marks?

Also, on question 9ii) I got an incorrect answer as when I substituted in the limits I rewrote ln(e^4) as e^4 instead of 4. However, I applied the limits correctly to the other variables. (And applied the correct method throughout) How many marks out of the 6 is this likely to have costed me?

Thanks a lot

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