OCR (not MEI) C2 - Wednesday 20th May 2015

Reply 160

lindtcrazy

Original post by eddy29

May just be me, but 12.7 isn't in the range of 0 to 2pi

The range is meant to be 0 to 6pi. The graph stretched by sf 3 in the x direction.

Reply 161

Renzhi10122

11

Original post by jamesplay73

I got the perimeter as 22.7

Same. I think you're right

Reply 162

Tobybeta

2

ARGGHHHHH...
Got all the questions right, apart from 9a) where I answered in degrees (I.e. 1080-a). There goes 3 marks :angry:

any guesses at what 70/72 is UMS wise? I probably get 1 on the 2 marker for method.

Reply 163

Mr_hawaii

Original post by ella_chloe

Anyone reckon 60 will be an a :/

lol, I would laugh

Reply 164

Jmedi

6

Original post by MrPenguinPerson

Same here I kept getting weird quadratics that didn't work, I have no idea what I was doing wrong... I have never seen a question like that in any c2 past papers before

For that question you set up the quadratic using the sum with 2N(continue sum formula) and then subtracting N-1 (and continuing sum formula) and hence you can set it up from there to get out 24 as the only viable solution

Reply 165

User10102929

1

Original post by Renzhi10122

Same. I think you're right

I did too

Reply 166

ZAK5YAK

4

Original post by AlistairMcDonald

I checked it manually, which was stupid, as I ran out of time by q9, but I got the same as he/she did

i got that answer at one point but cant remember if it was my final answer, i remember seeing i hadnt put brackets in on my calculator around the negative number and then i got a different answer surely if there is a negative number you put brackets around it? I might be wrong but just tryinh to see where i went wrong if i did!

Reply 167

Fletcher123

Any guesses as to what the grade boundaries and ums boundaries would be?

Posted from TSR Mobile

Reply 168

rich1334

11

Original post by Jmedi

For that question you set up the quadratic using the sum with 2N(continue sum formula) and then subtracting N-1 (and continuing sum formula) and hence you can set it up from there to get out 24 as the only viable solution

Yeah I did that several times and couldn't get a working quadratic. Must have made a silly arithmetic error. Hopefully get a few method marks

Reply 169

Simonium1010

7

Original post by xsanda

Xsanda's solutions:
R=-2
ar¹⁰ = 3072
Sum to 20 = -1048575

trapezium: 21.4
narrower strips

triangle area: 32.1
perimeter: 20.7

expansion: 64+192ax+240a²x²+…
a=2/3

y=4x^(3/2)-7x-3
(x-2)(x+5)(x-3)
256
negative section of integration counts negatively

u₂₀ = 62
Σ = 517 (show that)

N=24
n=17.1
x=32, y=8

6π-α
3π-a
graph of sin, half height
3.32, 12.7

Charlie that you?

Reply 170

gabby07

11

Original post by Fletcher123

Any guesses as to what the grade boundaries and ums boundaries would be?

Posted from TSR Mobile

My guess is 57 raw for an A

Reply 171

hattie.eatock

anyone know the answer to the 7 marker?

Reply 172

DominoMatrix227

2

Original post by AlistairMcDonald

How did you all find it? I didn't think it was too difficult, but I ran out of time before I could even look at 9, and it looked like quite a nice question, too :frown:

You didn't do any of 9? It was 9 marks!

Reply 173

Jmedi

6

Original post by rich1334

Yeah I did that several times and couldn't get a working quadratic. Must have made a silly arithmetic error. Hopefully get a few method marks

Yeah the only maybe other thing missed if it wasn't a arithmetic error was that in that bracket was N-2 instead of N-1.

Question;
Did the first part of Q9 have to be in radians? (The one referring to alpha and has anyone been able to confirm if the answer to the last part is 3.32 and 12.7? Those were my solutions however I'm very unsure in 12.7 )

Reply 174

sandpitturtle

6

Original post by Mr_hawaii

lol, I would laugh

laugh at what sorry?

Reply 175

Nuvertion

6

Original post by xsanda

Xsanda's solutions:
R=-2
ar¹⁰ = 3072
Sum to 20 = -1048575

trapezium: 21.4
narrower strips

triangle area: 32.1
perimeter: 20.7

expansion: 64+192ax+240a²x²+…
a=2/3

y=4x^(3/2)-7x-3
(x-2)(x+5)(x-3)
256
negative section of integration counts negatively

u₂₀ = 62
Σ = 517 (show that)

N=24
n=17.1
x=32, y=8

6π-α
3π-a
graph of sin, half height
3.32, 12.7

Wasn't this the answer for the sum? https://www.google.co.uk/search?q=(-2%5E19-1)%2F-2-1&rlz=1C1KMZB_enGB532GB532&oq=(-2%5E19-1)%2F-2-1&aqs=chrome..69i57.22447j0j7&sourceid=chrome&es_sm=93&ie=UTF-8#q=(3(((-2)%5E19)-1))%2F-2-1

Reply 176

gabby07

11

Can I just gauge how people felt that went, 1/10 being very badly, 10/10 being very well? Just so I get an idea of the standard. Reply to this post :smile:

Reply 177

username1967507

11

Original post by gabby07

Can I just gauge how people felt that went, 1/10 being very badly, 10/10 being very well? Just so I get an idea of the standard. Reply to this post :smile:

fairly straightforward 10/10

Reply 178

Renzhi10122

11

Original post by Nuvertion

Wasn't this the answer for the sum? https://www.google.co.uk/search?q=(-2%5E19-1)%2F-2-1&rlz=1C1KMZB_enGB532GB532&oq=(-2%5E19-1)%2F-2-1&aqs=chrome..69i57.22447j0j7&sourceid=chrome&es_sm=93&ie=UTF-8#q=(3(((-2)%5E19)-1))%2F-2-1

It was the sum of the first 20 terms, not the first 19 unfortunately