Mr M's OCR (not OCR MEI) Core 2 answers January 2012

Mr M's OCR (not OCR MEI) Core 2 answers January 2012

1. Sector of a circle

(i) Perimeter = 74.4 (3 marks)

(ii) Area = 302.4 (2 marks)

2. Trapezium rule

(i) 6.97 (4 marks)

(ii) Underestimate because the trapeziums are all below the curve (1 mark)

3. Binomial expansion

(i) a=0.5 (4 marks)

(ii) 4096 + 3072x (2 marks)

4. Ship and coastline

(i) 1.55 km (2 marks)

(ii) 124 degrees (3 marks)

(iii) 1.29 km (2 marks)

5. Cubic

(i) 36 (2 marks)

(ii)

(x-2)(2x^2+7x-3)

(4 marks)

(iii) 3 real roots as the discriminant is positive and there is a linear factor (2 marks)

6. Sequences

(i) 80, 75, 70 (2 marks)

(ii) 650 (3 marks)

(iii) p = 8 (4 marks)

(iv) 320 (2 marks)

7. Integration

(a)

\frac{x^4}{4}-2x^3+2x^2-24x+k

(3 marks)

(b) 4.4 (8 marks)

8. Logs

(a) 5.68 (4 marks)

(b) x=1/3 and y = 9 or x = 3 and y = 1 (6 marks)

9. Trig graphs

(i) Sketch correct graphs. Point (0, 3) needs to be marked. (3 marks)

(ii) Show given equation and the solutions are 2.02 and 4.26 (6 marks)

Shout at me if you think something is definitely wrong as I didn't have a calculator and some of these calculations are tricky on a computer!

woooo

Thanks, can I ask how you went about question 1 and why the intersection point is (0,3)?

Reply 3

Bristol Thriller

doesn't Q1 ask for the perimeter and area on the outside bit

Reply 4

OllieIsBareDumb

Bareeeee Dumb. The last question has 4 solutions. :mad:

Reply 5

Bristol Thriller

Original post by OllieIsBareDumb

Bareeeee Dumb. The last question has 4 solutions. :mad:

One of the sine values turns out to be a No Solution

Reply 6

Starlight94

Crapppp i did the solutions for question 9 wrong :frown:

i halved my answers instead of doubling them, so i had 1.1 but then halved it! ahh hopefully i'll still get some marks, also i got the integration question wrong, but hopefully i'll get some method marks. What do you think the grade boundaries will be?
Thankyou so much for posting this, it is greatly appreciated!

Reply 7

Jedicake

9

Whoops, forgot the +c on the integration...

Reply 8

IneedMentalHelp

If someone has paper, I would like to see. Thanks. :h:

Reply 9

OllieIsBareDumb

Original post by Bristol Thriller

One of the sine values turns out to be a No Solution

YES, DUH!

But the range is -2pi< x <2pi
So you so the answers are the 2.whatever and 4.whatever both answers minus 2pi.
Once again.
Nuff Dumb.

(edited 12 years ago)

Reply 10

Starlight94

can anyone remember the sequence and series question? i can't remember if i got those answers or not!

Reply 11

Thebestgod

Original post by Starlight94

can anyone remember the sequence and series question? i can't remember if i got those answers or not!

Yea...

Un=2n-5 I think.

(b) Sigma with n=20 on the top

U1, U3 and Up are terms of an arithnmetic progression where U1 and U3, Up3 form the 1st, 2nd and 3rd terms of a geometric progression. Find UP

Last one was Sum to infinity...

(edited 12 years ago)

Reply 12

Thebestgod

Original post by Starlight94

Crapppp i did the solutions for question 9 wrong :frown:

i halved my answers instead of doubling them, so i had 1.1 but then halved it! ahh hopefully i'll still get some marks, also i got the integration question wrong, but hopefully i'll get some method marks. What do you think the grade boundaries will be?
Thankyou so much for posting this, it is greatly appreciated!

Can you remember the Trig equation? Was something like...

3sin^2(1/2x)+5sin(1/2x)-3 right? Or was it 2sin^2?

Anyways, I've lost about 8 marks. Not too bad...

(edited 12 years ago)

Reply 13

Starlight94

Think i got around 50 marks :/

Reply 14

Starlight94

Original post by Thebestgod

Yea...

Un=2n-5 I think.

Thanks

can you remember the parts ii) and iii) by any chance too?

Reply 15

Thebestgod

Original post by Starlight94

Thanks

can you remember the parts ii) and iii) by any chance too?

Yea...

Un=2n-5 I think.

(b) Sigma with n=20 on the top

U1, U3 and Up are terms of an arithnmetic progression where U1 and U3, Up form the 1st, 2nd and 3rd terms of a geometric progression. Find UP

Last one was Sum to infinity.. I used r= 3/4 and got the right answer :smile:

(edited 12 years ago)

Reply 16

Jedicake

9

Original post by Thebestgod

Yea...

Un=2n-5 I think.

(b) Sigma with n=20 on the top

U1, U3 and Up are terms of an arithnmetic progression where U1 and U3, Up3 form the 1st, 2nd and 3rd terms of a geometric progression. Find UP

Last one was Sum to infinity.. I used r= 3/4 and got the right answer :smile:

Wasn't it

u_n = 85 - 5n

?

And I believe it was

u_1, u_5

and

u_p

?

(edited 12 years ago)

Reply 17

Thebestgod

I can remember the Binomial question too if that helps anyone...

(4+ax)^6 where 160x^3 is a term in the expansion

(i) Find the value of a. We know it's 1/2 now, great :smile:

(ii) Expand the first 2 terms of the expansion.

Logs...

7^(w-3)-5=180

(ii) The nasty simultaneous equation ...

log x + log y = 1 and log(3x+?)=3

something like that

I can't remember the ? haha :biggrin: