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

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

1. 6.39 (4 marks)

2. (i) 254 and 106 degrees (3 marks)

(ii) 71.6 and 252 degrees (3 marks)

3. (i)

64+960x+6000x^2

(4 marks)

(ii) c = - 11 (3 marks)

4. (a)

\frac{5}{4}x^4 -3x^2+x+k

(3 marks)

(b) (i)

-12 x^{-2} + k

(2 marks)

(ii) a = 2 (3 marks)

5. (i) 62.2 (4 marks)

(ii) 34.0 (4 marks)

6. (i) 963 (3 marks)

(ii) 17 (6 marks)

7. (i) Show ... (4 marks)

(ii)

\frac{37}{30}

(5 marks)

8. (i) (a) (0, 1) (1 mark)

b) (0, 4) (1 mark)

c) Any value where a > 1 and any value where 0 < b < 1 (2 marks)

(ii) Show ... (5 marks)

9. (i) 15 (2 marks)

(ii) Show f(-0.5)=0 and

f(x)=(2x+1)(2x-3)(x+1)

(6 marks)

(iii)

\theta = \frac{2\pi}{3}

and

\theta =\frac{4\pi}{3}

and

\theta=\pi

(4 marks)

I'll be around a bit this afternoon and then part of this evening to answer questions. Please post in this thread rather than sending me private messages.

(edited 10 years ago)

Scroll to see replies

Reply 1

kiraeil

Roughly what do you think the grade boundaries will be for an A?

Reply 2

kiraeil

For the area under curve question would I get some marks for workings as i worked out equation of tangent and area of small triangle but got complete wrong answer?
thanks

Reply 3

Mr M

Study Forum Helper

Original post by kiraeil

For the area under curve question would I get some marks for workings as i worked out equation of tangent and area of small triangle but got complete wrong answer?
thanks

Definitely.

Reply 4

Music99

For the area under the curve how many would I drop for, writing down it was the integral- the area of the triangle. I messed up calculating the x coordinate so in the end just guessed it as 2, in a last ditch effort :P

also for question 8 didn't b have to be a negative number?

(edited 10 years ago)

Reply 5

kiraeil

What was the working for 5ii) the question on finding the perimeter? Thanks.

Reply 6

eggfriedrice

Thanks Mr M! Looks like I made two stupid mistakes :/

Q3) I put 64+960x +3000x ^2
Q 4) ii a =1/2 (didn't notice the ^- so didn't flip)

How many marks lost?

Reply 7

milesw97

For question 9)ii) I inspected the cubic correctly to get a linear and a quadratic factor but somehow managed to get the + and - signs the wrong way round when I factorised by quadratic, getting (2x+3)(x-1). How many marks do you think this will cost me? Also, I then carried this error forwards into 9)iii) but used the correct method and got 2 of the 3 answers. Is there an allowance for error carried forwards or will I lose more marks here?

Reply 8

Blackfyre

Do you think that grade boundary for A might be 54 points as well?

Reply 9

eggfriedrice

Original post by Music99

Nope. Check your revision guide.

Reply 10

Majeue

Original post by kiraeil

What was the working for 5ii) the question on finding the perimeter? Thanks.

You had to work out the missing side using the cosine rule:
A^2=7^2+16^2-(2x7x16xcos0.8)
A=12.2
then you worked out arc length which is r x theta = 16x0.8 = 12.8
then you worked out the last side which was just 16-7=9
therefore, perimeter = 12.8+12.2+9 = 34

hope this helps

Reply 11

swaggy

Hey does anyone remember the questions for 5i), 5ii), 6i) 6ii) and 9i) please

Reply 12

CalBeans

I got the value for C as 24 and dont understand how it is -11 can you explain the answer in more detail please?

Reply 13

Majeue

Original post by eggfriedrice

Thanks Mr M! Looks like I made two stupid mistakes :/

Q3) I put 64+960x +3000x ^2
Q 4) ii a =1/2 (didn't notice the ^- so didn't flip)

How many marks lost?

1 for q3 and probably 2 for 4ii

Reply 14

milesw97

Original post by swaggy

Hey does anyone remember the questions for 5i), 5ii), 6i) 6ii) and 9i) please

5i) was the area of that portion of the sector with angle 0.8 radians, radius 16 and side length 7, you had to find the area of the whole sector and subtract the area of the triangle

(edited 10 years ago)

Reply 15

kiraeil

Thanks- If I worked out the missing side and arc length correctly but made a silly mistake for the length of the last side how many marks would i get. Thanks

Original post by Majeue

Reply 16

swaggy

Hey does anyone remember the questions for 5i), 5ii), 6i) 6ii) and 9i) please

Original post by milesw97

5i) was the area of that portion of the sector with angle 0.8 radians, radius 16 and side length 7, you had to find the area of the whole sector and subtract the area of the triangle

Oh thats right thanks :smile:

do you know the questions for 6, 7 and 9?

Reply 17

5foot

How many marks will I get for the area under the curve if I got the equation of the tangent wrong

Posted from TSR Mobile

Reply 18

Majeue

Original post by kiraeil

Thanks- If I worked out the missing side and arc length correctly but made a silly mistake for the length of the last side how many marks would i get. Thanks

I'd imagine you would get 2/4 marks.

Reply 19

Majeue

Original post by 5foot

How many marks will I get for the area under the curve if I got the equation of the tangent wrong

Posted from TSR Mobile

Maybe 1 or 2, depends if you did any part of it right or not because you only had to work out the area under tangent and were given the area under the other graph.