Mr M's OCR (not OCR MEI) Core 2 Answers May 2015

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Mr M
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Mr M's OCR (not OCR MEI) Core 2 Answers May 2015


1. (i) -2 (1 mark)

(ii) 3072 (2 marks)

(iii) -1048575 (2 marks)


2. (i) 21.4 (4 marks)

(ii) Increase the number of strips (1 mark)


3. (i) 32.1 (4 marks)

(ii) 22.7 (5 marks)


4. (i) 64+192ax+240a^2x^2 (4 marks)

(ii) \frac{2}{3} (3 marks)


5. y=4x^{\frac{3}{2}}-7x-3 (7 marks)


6. (i) f(x)=(x-2)(x-3)(x+5) (4 marks)

(ii) 256 (4 marks)

(iii) The graph has positive and negative y values across this interval (2 marks)


7. (i) 62 (2 marks)

(ii) Show (3 marks)

(iii) 24 (6 marks)


8. (a) 17.1 (4 marks)

(b) x = 32 and y = 8 (5 marks)


9. (i) (a) 6 \pi - \alpha (1 mark)

(b) 3 \pi - \alpha (2 marks)

(ii) Draw one period of the sine graph with half the amplitude of the cosine graph (2 marks)

(iiii) 3.32 and 12.7 (4 marks)
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ccfctom
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on the 2n (6) mark question, I worked out 2n - n, instead of 2n - (n-1).
I worked it out to obtain a quadratic, then used the quadratic formula and actually obtained N = 24, although the quadratic was incorrect. (think one value was like 24.34 so I rounded it to 24) and wrote N = 24
How many marks do you think I would get?
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Mr M
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(Original post by ccfctom)
on the 2n (6) mark question, I worked out 2n - n, instead of 2n - (n-1).
I worked it out to obtain a quadratic, then used the quadratic formula and actually obtained N = 24, although the quadratic was incorrect. (think one value was like 24.34 so I rounded it to 24) and wrote N = 24
How many marks do you think I would get?
You'll probably drop 2.
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Massi.scrase1
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N being 42 also worked out in the calculation didn't it?
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duncant
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thanks for posting. For 6(i) I wrote the three brackets but then a few lines underneath I wrote that x=2 etc. Would I still gain full marks?
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Mr M
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(Original post by Massi.scrase1)
N being 42 also worked out in the calculation didn't it?
No. That would produce 8213 rather than 2750 as the sum.
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username1006802
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(Original post by Mr M)
Mr M's OCR (not OCR MEI) Core 2 Answers May 2015


1. (i) -2 (1 mark)

(ii) 3072 (2 marks)

(iii) -1048575 (2 marks)


2. (i) 21.4 (4 marks)

(ii) Increase the number of strips (1 mark)


3. (i) 32.1 (4 marks)

(ii) 22.7 (5 marks)


4. (i) 64+192ax+240a^2x^2 (4 marks)

(ii) \frac{2}{3} (3 marks)


5. y=4x^{\frac{3}{2}}-7x-3 (7 marks)


6. (i) f(x)=(x-2)(x-3)(x+5) (4 marks)

(ii) 256 (4 marks)

(iii) The graph has positive and negative y values across this interval (2 marks)


7. (i) 62 (2 marks)

(ii) Show (3 marks)

(iii) 24 (6 marks)


8. (a) 17.1 (4 marks)

(b) x = 32 and y = 8 (5 marks)


9. (i) (a) 6 \pi - \alpha (1 mark)

(b) 3 \pi - \alpha (2 marks)

(ii) Draw one period of the sine graph with half the amplitude of the cosine graph (2 marks)

(iiii) 3.32 and 12.7 (4 marks)

Many thanks again Mr M for posting this. Just wanted to check a few things if it's okay with you.
1. I put increase the number of strips i.e. n and/or use narrower strips. Would I still get the mark?
2.for 6iii I put that between x= -5 to x = 2 the graph is below x axis and between x=2 to x =3 the graph is above. How many marks do you think I could get for that?
3.for 9ii I drew the graph with half the amplitude however also stretched it by 1/3 in x axis which I know is wrong so would I get 1 mark for this ?
4. Finally, for the last question I did it wrong but I did get tan0.5x so would I get a mark for turning the given equation into terms of tan?

Your help is much appreciated so many thanks for everything!
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Wolfram74
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Mr M, how many marks would I get for the 2N N question if I used N instead of N - 1 and obtained a quadratic, then attempted to complete the square on that quadratic to find N? Also would I get a mark for drawing the graph but not stating why the area was not the same as the integral?
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Suprajaa
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Thank you so much:

Firstly on question 5, I didn't use the gradient in my question so I differentiated twice and got the first part of the answer, how many marks would I lose?

On 7iii) I only found out the sum of 2N and had that equal to 2075 (I think was the number) and found a quadratic from that, have I lost all my marks for that question?

And on 8b) I substituted x into the x^2 equations and expanded it out but I couldn't figure out what to do after that, would that give me two marks?


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Mr M
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(Original post by zintanax)
Many thanks again Mr M for posting this. Just wanted to check a few things if it's okay with you.
1. I put increase the number of strips i.e. n and/or use narrower strips. Would I still get the mark?
2.for 6iii I put that between x= -5 to x = 2 the graph is below x axis and between x=2 to x =3 the graph is above. How many marks do you think I could get for that?
3.for 9ii I drew the graph with half the amplitude however also stretched it by 1/3 in x axis which I know is wrong so would I get 1 mark for this ?
4. Finally, for the last question I did it wrong but I did get tan0.5x so would I get a mark for turning the given equation into terms of tan?

Your help is much appreciated so many thanks for everything!
1. Fine

2. You have that the wrong way round. Drop 1.

3. Yes

4. Possibly
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ccfctom
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For 6 iii) I drew the graph correctly and shaded the area under the curve, but I wrote "area under curve not calculated"

would this get 1 or 2 marks?
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Mr M
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(Original post by Wolfram74)
Mr M, how many marks would I get for the 2N N question if I used N instead of N - 1 and obtained a quadratic, then attempted to complete the square on that quadratic to find N? Also would I get a mark for drawing the graph but not stating why the area was not the same as the integral?
You could probably get up to 4 on 6(iii) and drop 1 on the graph question.
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Mr M
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(Original post by Suprajaa)
Thank you so much:

Firstly on question 5, I didn't use the gradient in my question so I differentiated twice and got the first part of the answer, how many marks would I lose?

On 7iii) I only found out the sum of 2N and had that equal to 2075 (I think was the number) and found a quadratic from that, have I lost all my marks for that question?

And on 8b) I substituted x into the x^2 equations and expanded it out but I couldn't figure out what to do after that, would that give me two marks?


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5) no marks if you differentiated - if you integrated twice probably four marks

7iii) you might get one or two marks

8b) yes
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Mr M
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(Original post by ccfctom)
For 6 iii) I drew the graph correctly and shaded the area under the curve, but I wrote "area under curve not calculated"

would this get 1 or 2 marks?
You might get 2 if your examiner is lenient!
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mja2106
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Could someone please remind me what question 7i was please ?
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heytherehey
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Sir, I have three queries.
1. for the 7 marker integratio q i made a silly msitake with my second integration part but i did the method correct (how many marks will i lose)
2. For the last question I got them right but i was silly and put my answer in degrees (would they penalise me throughout) How many marks will i lose)

Finally, surely this paper was harder than last years where the A was 56 yet surely they cant go lower than that for a C2 paper?
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Mr M
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(Original post by mja2106)
Could someone please remind me what question 7i was please ?
a=5
r=3
Find the 20th term of the GP
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Mr M
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(Original post by heytherehey)
Sir, I have three queries.
1. for the 7 marker integratio q i made a silly msitake with my second integration part but i did the method correct (how many marks will i lose)
2. For the last question I got them right but i was silly and put my answer in degrees (would they penalise me throughout) How many marks will i lose)

Finally, surely this paper was harder than last years where the A was 56 yet surely they cant go lower than that for a C2 paper?
1. I don't know what the silly mistake was. You should still be able to get 5 marks.

2. I expect there will be an instruction to only penalise degrees once - lose 1 mark in total.
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Wolfram74
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Also, was it necessary to state the coordinates of the intercepts with the axes on 6(iii)?
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Suprajaa
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(Original post by Mr M)
5) no marks if you differentiated - if you integrated twice probably four marks

7iii) you might get one or two marks

8b) yes
Sorry I meant integrated, so I would lose four marks, or gain them??


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