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OCR C2 exam Wed 25th May

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Reply 200

AvKar

Original post by GPW333

What was question 6 about?

Something to do with AP and GP - you were given Un+1 in part i) I think

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Reply 201

AvKar

Original post by proximity

Someone please send in their solution of the integration question with answer 512/15

Do you remember the exact question?

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Reply 202

micycle

Original post by AlfieH

My teacher has confirmed that the answer to 9iii is Pi/3a and 4Pi/3a.

Unless i'm wrong, with Pi/3A, you're multiplying by A twice.

The solution is 5/3 * 1/5Pi, which equals 1/3Pi but not 1/3Pi times by another A.

Reply 203

Jamesk123

Original post by AlfieH

I am gonna start an unofficial mark scheme - I think this is about correct! :smile:

1i) 10cm (2m)

1ii) 5.04cm (2m)

2i) 3/10π (2m)

2ii) 20.4cm (3m)

3i) 27+27kx+9k^2x^2+k^3x^3 (4m)

3ii) +/-√3 (2m)

4i) log base 3 x^2/x+4 (2m)

4ii) x=12 (4m)

5a) x^4/2-x^3+2x^2-6x (3m)

5bi) -6/a+2/a^2+4 (4m)

5bii) 4 (1m)

6i) k=91 (3m)

6ii) Sum of terms = 978 (2m)

6iii) N=38 (6m)

7i) R=0, quotient = x^2-4x+3 (3m)

7ii) (x+1), (x-1), (x-3) (3m)

7iii) Prove (2m)

7iv) 512/15 (4m)

8i) Translation 2 units in positive x direction (2m)

8ii) Stretch scale factor 1/9 in y direction (2m)

8iii) Sketch, crosses y at (0,1/9) (2m)

8iv) x=6.73 (3m)

8v) Area =9.60 (3m)

9i) 2π/a (1m)

9ii) a=5/3 and k=√3/2 (3m)

9iii) π/3a and ? (4m)

8 iii and 9 iii were both 3 marks I think

Reply 204

student.1997

Does anyone remember roughly what the questions were for these answers?
5bi) -6/a+2/a^2+4 (4m) 8iv) x=6.73 (3m)

Reply 205

DziNe

For the last part of question 9, I answered in degrees and not radians (60/a and 180 - 60/a) - the question didn't ask for radians did it so I'd still get all the marks?

Reply 206

CLGC98

Original post by proximity

Someone please send in their solution of the integration question with answer 512/15

Thank god, loads of people said you were meant to split it out and I didn't .

Reply 207

Jamesk123

Original post by CLGC98

How were you meant to do the integration to find the area , was it with limits of 3 to -1 or do you do -1 to 0 and 0 to 3?

3 to -1

Reply 208

CLGC98

Original post by DziNe

For the last part of question 9, I answered in degrees and not radians (60/a and 180 - 60/a) - the question didn't ask for radians did it so I'd still get all the marks?

It did say radians

Reply 209

AlfieH

Original post by louisa190

for definite?

Yep!

Reply 210

micycle

Original post by DziNe

For the last part of question 9, I answered in degrees and not radians (60/a and 180 - 60/a) - the question didn't ask for radians did it so I'd still get all the marks?

http://static1.squarespace.com/static/52c1f91ee4b0a77a50337e61/t/56bf9e372fe1311b18cf8311/1455398643424/OCR+C2+June+2015+mark+scheme.pdf

^ Last yea's mark scheme. Question 9 on that was very similar. They state explicitly that the answer "Must be radians and not degrees" but gave a method mark if "attempted in degrees not radians".

Reply 211

Jamesk123

Can someone go through the area under curve one please? I got the intervals as 3 and -1 and integrated right but then somehow went wrong

Reply 212

Karmen99

Original post by cc262626

For the coeffient is equal to the constant question, did anyone else think they meant the constant k? And get answers of 1/9 and 0 😟

I did the same but since they didn't make it clear I think they should accept both answers

Reply 213

Alevelz

Does anyone remember the exact geometric question where you had to find N that's greater than infinity?

Reply 214

abrahammurciano

Original post by Alevelz

Does anyone remember the exact geometric question where you had to find N that's greater than infinity?

N=38

Reply 215

Alevelz

No I mean the question but thanks

Reply 216

morrissies

Original post by Alevelz

Does anyone remember the exact geometric question where you had to find N that's greater than infinity?

not word for word but it was:
sum of first 20 terms of AP > sum to infinity of GP

(for the AP a=5 d=1.5) (for the GP a=1.2 (?) r=0.9)

Reply 217

Karmen99

Original post by CLGC98

How were you meant to do the integration to find the area , was it with limits of 3 to -1 or do you do -1 to 0 and 0 to 3?

I think it was -1 to 3 since the the are was above the axis, you only split it if it's part below part above. That's what I think anyway (might be wrong)

Reply 218

micycle

Original post by Alevelz

Does anyone remember the exact geometric question where you had to find N that's greater than infinity?

37.27 > N

So 38 is the smallest whole number N can take.

(edited 7 years ago)

Reply 219

abrahammurciano

Original post by iamDev

I was thinking you were right but the period isnt 2pi over a. 2pi over a is the period of a sin ax graph not a tan ax graph

u ARE supposed to use the period of the sin or cos graph... NOT the tan graph.
At the end of the day, the tan graph will give you many possible solutions, but the ones required by the question are the ones where the sin and cos are positive, so u work it out using the period of the sin and cosine in the quadrants where both sin and cos are positive