Mr M's OCR (not OCR MEI) Core 2 Answers 18th January 2013

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Reply 40

alexj1790

Ok cool, was just wondering as I had the s2 exam today :wink:

Reply 41

natashaei123

How am i able to find the paper questions for both core1 and core2 please?

Reply 42

DocHama

Original post by Mr M

Mr M's OCR (not OCR MEI) Core 2 Answers January 2013

1. (i) 39.5 degrees (2 marks)

(ii) 15.3 cm (2 marks)

2. (i) Show ... (2 marks)

(ii) Show ... (4 marks)

3. (i)

k=\frac{3}{2}

(2 marks)

(ii)

y=x^3-\frac{3x^2}{4}+2

(5 marks)

4. (i)

32+80x+80x^2+40x^3+10x^4+x^5

(4 marks)

(ii) 1560 (3 marks)

5. (i) Show ... (3 marks)

(ii) x = 120 degs, 240 degs, 48.2 degs, 312 degs (4 marks)

6. (i)

x=\frac{15}{2}

(3 marks)

(ii) (a) Verify and

S_{\infty}=64

(4 marks)

(b)

x=-\frac{2}{3}

(4 marks)

7. (i) Show ... (2 marks)

(ii) 15.2 cm (2 marks)

(iii) 9.76 cm^2 (5 marks)

8. (i) Translation by 3 units in the positive x direction (2 marks)

(ii) a = 8 (1 mark)

(iii) b = 6.48 (2 marks)

(iv)

c=\frac{16}{5}

(4 marks)

9. (i) Show ... (6 marks)

(ii)

a=\frac{1+\sqrt{7}}{3}

(6 marks)

Hi, thanks for the answers, just one Q., wouldn't the last one be (1+or-rt7) /3 ? or is the (1-rt7)/3 not included? Also how many marks would you loose if you put both? Thanks :smile:

Reply 43

cleverslacker

Muchos Gracias Mr. M
Major improvement to June I think.
Hope you're covering C3 next week!

Reply 44

DocHama

Original post by Lstigant

Why is 6ii 64?? I got r=3/4 so 8/(1-3/4)=32

'a' was 2x, when x=8, 2x=16, hence 16/(1-3/4) is 64 :frown:

Reply 45

olivers16

If I didn't round my answers (especially for the first 2 questions) and it doesn't say anything on the question like 3 sig fig, will I lose any marks? Thanks.

Reply 46

Mr M

Study Forum Helper

Original post by BawanHama

Hi, thanks for the answers, just one Q., wouldn't the last one be (1+or-rt7) /3 ? or is the (1-rt7)/3 not included? Also how many marks would you loose if you put both? Thanks :smile:

The question says it has to be positive. Drop 1 mark.

Reply 47

Mr M

Study Forum Helper

Original post by cleverslacker

Muchos Gracias Mr. M
Major improvement to June I think.
Hope you're covering C3 next week!

Yes.

Reply 48

Mr M

Study Forum Helper

Original post by olivers16

If I didn't round my answers (especially for the first 2 questions) and it doesn't say anything on the question like 3 sig fig, will I lose any marks? Thanks.

The exam papers for all OCR A Level maths exams say on the front to round all non-exact answers to 3 s.f.

If you gave more accurate answers than this, you will not be penalised.

Reply 49

AdamSutton

What if I did 1/3 + 1/3root7? how many marks would I lose? t

Original post by Mr M

Mr M's OCR (not OCR MEI) Core 2 Answers January 2013

1. (i) 39.5 degrees (2 marks)

(ii) 15.3 cm (2 marks)

2. (i) Show ... (2 marks)

(ii) Show ... (4 marks)

3. (i)

k=\frac{3}{2}

(2 marks)

(ii)

y=x^3-\frac{3x^2}{4}+2

(5 marks)

4. (i)

32+80x+80x^2+40x^3+10x^4+x^5

(4 marks)

(ii) 1560 (3 marks)

5. (i) Show ... (3 marks)

(ii) x = 120 degs, 240 degs, 48.2 degs, 312 degs (4 marks)

6. (i)

x=\frac{15}{2}

(3 marks)

(ii) (a) Verify and

S_{\infty}=64

(4 marks)

(b)

x=-\frac{2}{3}

c=\frac{16}{5}

(4 marks)

9. (i) Show ... (6 marks)

(ii)

a=\frac{1+\sqrt{7}}{3}

(6 marks)

Reply 50

Mr M

Study Forum Helper

Original post by AdamSutton

What if I did 1/3 + 1/3root7? how many marks would I lose? t

You wouldn't lose any as that is the right answer (unless you have put that root 7 on the bottom of the second fraction)!

Reply 51

PhysMathEcon

How many marks would you guess this is worth as obviously it's slightly wrong

Y+4= log2(c) y= log2(c-3)
Log2(c) - log2(8)= log2(c-3)
c/8=c-3
7c=24
c= 3.24

Thanks

Original post by Mr M

Mr M's OCR (not OCR MEI) Core 2 Answers January 2013

1. (i) 39.5 degrees (2 marks)

(ii) 15.3 cm (2 marks)

2. (i) Show ... (2 marks)

(ii) Show ... (4 marks)

3. (i)

k=\frac{3}{2}

(2 marks)

(ii)

y=x^3-\frac{3x^2}{4}+2

(5 marks)

4. (i)

32+80x+80x^2+40x^3+10x^4+x^5

(4 marks)

(ii) 1560 (3 marks)

5. (i) Show ... (3 marks)

(ii) x = 120 degs, 240 degs, 48.2 degs, 312 degs (4 marks)

6. (i)

x=\frac{15}{2}

(3 marks)

(ii) (a) Verify and

S_{\infty}=64

(4 marks)

(b)

x=-\frac{2}{3}

c=\frac{16}{5}

(4 marks)

9. (i) Show ... (6 marks)

(ii)

a=\frac{1+\sqrt{7}}{3}

(6 marks)

Reply 52

olivers16

Original post by Mr M

The exam papers for all OCR A Level maths exams say on the front to round all non-exact answers to 3 s.f.

If you gave more accurate answers than this, you will not be penalised.

Great thank you

Reply 53

stirkee

Original post by PhysMathEcon

How many marks would you guess this is worth as obviously it's slightly wrong

Y+4= log2(c) y= log2(c-3)
Log2(c) - log2(8)= log2(c-3)
c/8=c-3
7c=24
c= 3.24

Thanks

what on earth did you do there :eek:

1 maybe, dunno

Reply 54

Mr M

Study Forum Helper

Original post by PhysMathEcon

How many marks would you guess this is worth as obviously it's slightly wrong

Y+4= log2(c) y= log2(c-3)
Log2(c) - log2(8)= log2(c-3)
c/8=c-3
7c=24
c= 3.24

Thanks

That's really wrong. Probably worth 1 mark.

Reply 55

JASApplications

on 7iii) I really hadn't got a clue what to do so ended up plugging numbers in the two area formulas (1/2absinC and 1/2r^2theta)

I worked out the area of the triangle and multiplied by 2 to get about 25.2. I worked out the area of the sector and multiplied by 2 to get about 53.0. I then subtracted the area of the triangle from the area of the sector and ended up with around 27cm^2!

Doesn't really make sense but I had 5 mins left at the end of the exam so had to try something!

How many method marks do you thing I would get? 2/5? 3/5 at a push?

Reply 56

PhysMathEcon

Original post by Mr M

That's really wrong. Probably worth 1 mark.

Ok Thankyou, where else is wrong as the only mistake I can see is that I wrote 4 to be log2(8) rather than log2(16), and then ofcourse the answer as a result, correcting 8 to 16 using the same method gives the correct answer.
I'm not arguing your reply, you definitely know best, I'm just curious and ofcourse would llike to believe there is a chance of 2 :smile:

Reply 57

mcfc@2012

Original post by Mr M

That's really wrong. Probably worth 1 mark.

I think that's very nearly right, surely he would get method marks?

Reply 58

CocoTango

YAY! These threads make me feel so much better - before I thought I'd got a C but now I reckon I've got an A - thank you so much!

But for the penultimate question ... What would the algebraic integral be ( before you put in the a values)