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Mr M's OCR (not OCR MEI) Core 2 Answers May 2012 <strong><font

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Reply 60
Avatar for Ursin
Ursin
14
Mr M,
If I wrote the three values for question 4, but also 270, will I lose marks? If so how many? Thanks
Reply 61
Avatar for J.C
J.C
If I'm remembering all my answers right I should hopefully get 69/72. Was aiming for full marks but that damn obtuse angle question got me. Still good though.
My answers to question 7i and ii were divided by roots and I didn't think to rationalise them (otherwise answer correct), will it be ok?
Original post by whitenosugar
Hi Mr M,

For question 4, I used the right trig identities and got to 4sin^2x - 7sinx + 3 = 0 (not sure if I've remembered it correctly) but then I must've stupidly factorised it wrong and ended up with x= 30, 150.

Do you think I'd get any of the 6 marks, seeing as my method was correct(ish)?

Thankyou!


You will get 2 marks.

Bet you factorised it as (2 sinx - 1)(2 sin x -3) instead of (4 sin x - 3)(sin x -1)
Original post by jodiedoodles
Thanks! Sorry to be a pain but do you have any idea how many raw marks around 75-80 UMS would need? :smile:


Not really
Re the periodic sequence, is saying that it oscillates between 4 and 1/2 also a valid answer?
Original post by Janet9311
Hello Mr M,
If I wrote 2sqrt10/7 for 7(ii), how many marks will I lost?


drop 1
Reply 67
Avatar for Ursin
Ursin
14
Original post by Mr M
It isn't a solution - I don't know where your 270 came from?

I stupidly thoght 90 add another 90 for the reflection...I don't know why I thought that.
Reply 68
Avatar for KS8
KS8
Looks like I've done well but I didn't have time to go back and check everything. :facepalm2:

Mr. M, on the question where you had to work out the segment, I got the correct answer but used the formula

Area = (1/2)r^2(theta - sin(theta))

Would I be ok for the marks here or are some marks awarded for showing that you can apply the area of a triangle formula and subtract that from the sector area? Whereas I just used the above formula to jump straight to the answer.
Original post by propertimbo
On the last question I got y to equal -1 would I get any method marks or none at all?

This was posted from The Student Room's Android App on my HTC One X


I don't know what you did so can't say but it doesn't look promising.
I stupidly didn't read the pi after the 45 in question 3, but did everything else right. How many marks will i lose? Also if you left the answer as 5/root 29 for 7ai will you lose any marks seeing as it was just a 2 mark question? Also for the 2nd part I got the right answer (apart from minus sign), but again didn't simplify my surd. do you reckon I'll have lost any marks?
Reply 71
Avatar for saj1994
saj1994
HI Mr M,

On Q2ii) i got the wrong value for c instead of getting -4 i got -22, i did all the working out correct but i think its a calculation error, how many marks would i get for this?

On Q5aii) I put the sequence repeats itself every 2 terms, would i get a mark for this.

On Q7 I used the SOH CAH TOA rule and the pythagoras rule to get different answers would get any marks for this.
Original post by Millyshyn
My answers to question 7i and ii were divided by roots and I didn't think to rationalise them (otherwise answer correct), will it be ok?


yes that's fine
Original post by Mr M
I don't know what you did so can't say but it doesn't look promising.


Mr M last question please, Do you think this papers was hard relative to the other c2 papers, also what raw mark do you think will be an A, Thanks
Original post by KS8
Looks like I've done well but I didn't have time to go back and check everything. :facepalm2:

Mr. M, on the question where you had to work out the segment, I got the correct answer but used the formula

Area = (1/2)r^2(theta - sin(theta))

Would I be ok for the marks here or are some marks awarded for showing that you can apply the area of a triangle formula and subtract that from the sector area? Whereas I just used the above formula to jump straight to the answer.


I did the same as you - it's fine
Original post by Ursin
Mr M,
If I wrote the three values for question 4, but also 270, will I lose marks? If so how many? Thanks


drop 1 mark
Thank you so much Mr M! This is incredibly helpful.


So cross about question 7 >:frown:





Edit: Ok usually I don't mind negs but really? What did I do for that?
(edited 11 years ago)
Original post by Snakefingers13
Re the periodic sequence, is saying that it oscillates between 4 and 1/2 also a valid answer?


yes
Original post by Mr M
You will get 2 marks.

Bet you factorised it as (2 sinx - 1)(2 sin x -3) instead of (4 sin x - 3)(sin x -1)


Yeah I did you're right! really kicking myself now, but thankyou!
Reply 79
Avatar for J DOT A
J DOT A
Original post by Mr M
drop 1


Yeah MR M, I used the formula for segment...A=0.5r^2(theta-sintheta) with a value of 15/sqrt pi, would I get 2 method marks out of 3 for using the formula?
It's just that my r value was incorrect.

Also, You said I might loose 2 marks for getting incorrect r value..but wouldn't there be on for method?

Finally, for 7ii I got that answer but postive, I used a triangle and did the acute angle..how many marks would I drop?

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