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# Ocr Mei C4 15/1/10 watch

1. Haha i got THE MATHEMATICIAN SPAT....oh deary me.
2. (Original post by sinesquared.)
Haha i got THE MATHEMATICIAN SPAT....oh deary me.
you only had to find the first 16 letters!
3. what did you get for the parrtial fractions part of the last question, 1,1,1??
4. (Original post by Annecejones)
you only had to find the first 16 letters!
Oh dear lord.
Im am such an idiot...do you think i will not get that mark for doing more..yeh probably. Oh.
5. (Original post by Annecejones)
what did you get for the parrtial fractions part of the last question, 1,1,1??
A=1
B=1
C=1
?
Thats what i got...i checked it a few times..because i thought hang on all ones really..no nasty minuses anywhere?
6. (Original post by sinesquared.)
Oh dear lord.
Im am such an idiot...do you think i will not get that mark for doing more..yeh probably. Oh.
you might be lucky because it will probably make your marker laugh!
7. (Original post by sinesquared.)
A=1
B=1
C=1
?
Thats what i got...i checked it a few times..because i thought hang on all ones really..no nasty minuses anywhere?
yeah... it made me a bit suspicious too
8. (Original post by Undulipodium)
Yup - then solve tanx = -1 and 1/3, getting 4 values.
Do you remember what 4 values you got? just i didnt get 4-now im thinking i am sadly mistaken! x
9. (Original post by missrosiex)
Do you remember what 4 values you got? just i didnt get 4-now im thinking i am sadly mistaken! x
I don't have a calculator on me, but if you arctan the values (-1 & 1/3) you should get the four values - the second two by adding 180 degrees to the first two values.
10. (Original post by Recluse)
For the verifying part, after you differentiated, you just needed to sub in the x value and show you got the same derivative they had, then you can say the x value is a valid solution to the differential equation. And like some others said, sub'ing in the x,y values allowed you to say that they were valid solutions also.

I remember the partial fractions question came out as something + something + somthing, and when you came to integrate, you had to take a factor of -1 out of one of the logarithms which gave you the foundations of using that division log identity.

The trig question was easy. Some friends at my college couldn't do the 'find theta when AB is horizontal part', but all you needed to do was put h = 0 and tidy up (I swear I'd done this question before as well, did anyone else think that? Can't remember where though).

I don't think I dropped any marks on the paper.

some plain text messages I got were

THE MATHEMATICIAN
LKOK (which I thought might be wrong, because it's too close to LOOK! I screwed it up with 20 seconds left and had to rush.)

For the part when they wanted you to explain why 2,4 were the only possibilities, I just said that GCD(84, 40) = 4, and 2 is a factor of 4..

For the part about why a keyword of length 2 is less secure than one of length 4, I said something about it being more likely to have repeating letters in the cipher text, and also that obviously 2! < 4! (I then calculated some probabilities)

About all I can remember cleary :P

C3 & S3 on the 20th! Good luck.
It was FACE not LOOK.

Also, the key length is because it gives fewer, longer strings (= better frequency analysis = easier decryption.)
11. (Original post by Undulipodium)
I don't have a calculator on me, but if you arctan the values (-1 & 1/3) you should get the four values - the second two by adding 180 degrees to the first two values.
ahh yeah.But for arctan-1 i got -45 so discounted it from the range but did do -45 from 180 and got three..oh well can't change it now i was wrong to assume i believe! x
12. (Original post by missrosiex)
ahh yeah.But for arctan-1 i got -45 so discounted it from the range but did do -45 from 180 and got three..oh well can't change it now i was wrong to assume i believe! x
You were right to discount -45, but the values from it were (180-45) and (-45+180+180).
13. ohh cool thankyou,so i might still get some of the marks,ahh i understand that though now you said!

thanks x
14. (Original post by Undulipodium)
You were right to discount -45, but the values from it were (180-45) and (-45+180+180).
Try doing on a calculator:

It comes out as a solution to the equation because it's a "tending to" kind of thing, but unfortunately it's still undefined, so I don't think you can list those two as solutions.

But I'm not sure.
I sort of wrote them and then said, but ignore those two values, Mr. Examiner!
15. (Original post by Recluse)
For the verifying part, after you differentiated, you just needed to sub in the x value and show you got the same derivative they had, then you can say the x value is a valid solution to the differential equation. And like some others said, sub'ing in the x,y values allowed you to say that they were valid solutions also.

I remember the partial fractions question came out as something + something + somthing, and when you came to integrate, you had to take a factor of -1 out of one of the logarithms which gave you the foundations of using that division log identity.

The trig question was easy. Some friends at my college couldn't do the 'find theta when AB is horizontal part', but all you needed to do was put h = 0 and tidy up (I swear I'd done this question before as well, did anyone else think that? Can't remember where though).

I don't think I dropped any marks on the paper.

some plain text messages I got were

THE MATHEMATICIAN
LKOK (which I thought might be wrong, because it's too close to LOOK! I screwed it up with 20 seconds left and had to rush.)

For the part when they wanted you to explain why 2,4 were the only possibilities, I just said that GCD(84, 40) = 4, and 2 is a factor of 4..

For the part about why a keyword of length 2 is less secure than one of length 4, I said something about it being more likely to have repeating letters in the cipher text, and also that obviously 2! < 4! (I then calculated some probabilities)

About all I can remember cleary :P

C3 & S3 on the 20th! Good luck.
I did this verification too.
And then spent ages actually solving it properly in order to do the next part of the question.

Of course, I wrote a bit of a narky note to the examiner saying that it should have been "show that" or something rather than "verify"!

And yes - C3 and S3 for me on the 20th too - good luck, m'laddio!
16. After section A I was thinking how well it was going. Then I thought, 'crap. I'll have jinxed it now'
Question 6 was fine but I completely ****** up question 7.

The comprehension was fine but I finished after 15 minutes and we weren't allowed out so I had to sit there for the rest of the time, ridiculously bored.

The whole of the thing on the back was 'The mathematician's patterns like the painter's or the poet's must be beautiful. The ideas, like the colours or the words must fit together in a harmonious way. There is no room in this world for ugly mathematics'
17. (Original post by bubblle)
The whole of the thing on the back was 'The mathematician's patterns like the painter's or the poet's must be beautiful. The ideas, like the colours or the words must fit together in a harmonious way. There is no room in this world for ugly mathematics'

Ahh it makes sense now..
18. (Original post by bubblle)
After section A I was thinking how well it was going. Then I thought, 'crap. I'll have jinxed it now'
Question 6 was fine but I completely ****** up question 7.

The comprehension was fine but I finished after 15 minutes and we weren't allowed out so I had to sit there for the rest of the time, ridiculously bored.

The whole of the thing on the back was 'The mathematician's patterns like the painter's or the poet's must be beautiful. The ideas, like the colours or the words must fit together in a harmonious way. There is no room in this world for ugly mathematics'
Ah thanks for solving it I wondered what it was. You never know you might get a bonus mark, although there was a not on the piece saying don't try and solve or check the ciphers. Fortunately our school did let us leave early, so I went after around 25 minutes, but there was only 16 of us doing C4 in the exam hall.
19. (Original post by Chriz M)
Ah thanks for solving it I wondered what it was. You never know you might get a bonus mark, although there was a not on the piece saying don't try and solve or check the ciphers. Fortunately our school did let us leave early, so I went after around 25 minutes, but there was only 16 of us doing C4 in the exam hall.
I didn't write out the whole thing on the paper, I just read it at the end when I was bored...
We had like 30 people doing it and they told us at the beginning that we would have to stay there for the whole time... so annoying!
20. (Original post by sinesquared.)
Ahh it makes sense now..
Haha, did you think it said "the mathematician spat" for ages too?

I just got completely muddled up with the grammar, and in the end decided that I should check my answers instead

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