The Student Room Group

let's talk about our maths exams, 1st year Cambridge people

Fellow 1st-year Cambridge mathmos - how's your revision going?

Good luck to tommm, marers, wooper, and everyone else! :smile:

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Reply 1
Hello :smile:

My motivation to work varies too much. I'm not in the mood at all today.

My chances on each paper:
1 - V+M is easier than it seems, the lecture notes are far too in depth for the exam questions that appear to be set. As much as I like Analysis, the questions tend to be pretty hard. I've learnt all the standard proofs, and I'll see what I can do from there.
2 - I'll probably do best in this paper. I've spent a couple of days revising probability and I've realised I can actually do quite a large amount of it. Differential Equations is relatively straightforward. I think I'll be able to attempt 5 section II questions on this one.
4 - I'm not very good at D+R, and N+S is pretty variable. I'll struggle on this paper unless I'm lucky with the questions that come up.
3 - VC is my favourite course, Groups is my least favourite course. This makes me very glad that there are no compulsory questions.

Good luck to everyone :smile:
Reply 2
Good luck stripy, tommm, wooper!

Are we the only first-years here? :smile:

"No one in their right mind would stay at this hotel... A guest can (and should) escape into the street" - still laughing at that question! :smile:
Reply 3
Original post by tommm
Hello :smile:

My motivation to work varies too much. I'm not in the mood at all today.

My chances on each paper:
1 - V+M is easier than it seems, the lecture notes are far too in depth for the exam questions that appear to be set. As much as I like Analysis, the questions tend to be pretty hard. I've learnt all the standard proofs, and I'll see what I can do from there.
2 - I'll probably do best in this paper. I've spent a couple of days revising probability and I've realised I can actually do quite a large amount of it. Differential Equations is relatively straightforward. I think I'll be able to attempt 5 section II questions on this one.
4 - I'm not very good at D+R, and N+S is pretty variable. I'll struggle on this paper unless I'm lucky with the questions that come up.
3 - VC is my favourite course, Groups is my least favourite course. This makes me very glad that there are no compulsory questions.

Good luck to everyone :smile:


Learn countability really well (the questions are all mostly the same anyway). Inclusion-exclusion comes up pretty often as well, and that's not too hard either.

also, DE 2010 was an absolute nightmare, so chances are it will probably be a little easier this year.
Reply 4
Original post by around
also, DE 2010 was an absolute nightmare, so chances are it will probably be a little easier this year.


I don't think any course will be easier than last year. Our papers seemed to have been viewed as a bit too easy (given how high the boundaries were) and so I'd expect the exams to be harder this year.

Not to panic any of you :smile:
Reply 5
I'm guessing 2 alphas, 4 betas today. Maybe one of the betas is an alpha. Very pleased.
Reply 6
Where's everyone else gone? :frown:
Reply 7
Hi everybody :smile: Fairly nice paper. I really liked question 10 (fixed points of functions - answers no, no, no, yes), but question 5 (equations of lines and planes) took ages.
Reply 8
Very pleased with how that went!
Reply 9
Yep, Paper 2 wasn't bad :smile: A few wacky probability questions - Grimmett, no doubt :rolleyes:

The prince and pea question was pretty easy. What did people say in the volcano question about interpreting phi in terms of U?

I did question 7 because past questions about Wronskians have usually been straightforward, but this one was peculiar! I wrote that the answer should be yes in b), because (sin x) and (1 + cos x) are clearly linearly independent, regardless of the fact that the Wronskian is zero at pi. Then right after the exam (!), I realised why there is no contradiction from Abel - because p and q are discontinuous at every point at which W = 0.
Reply 10
I did all three probability questions except the volcano one, and I think I did two of them well, and the other I just struggled to find the mean with that binomial coefficient in it. Did you get 64/9 for the pea/mattress/prince question, and 51 (which, intuitively, seems unreasonably high) for the mean time to absorption?

Did two DEs: the system of equations with the μ\mu in it that needed linearising, which I was pleased with, and the Wronskian one - I said no to b) because the singularity at pi means that weird stuff that I didn't phrase very well can happen. I also did a section I question about stability.

Overall, incredibly happy. I never thought I'd be able to do that many questions well. I just hope I get alphas in the ones I did about 3/4 of...
Reply 11
For the wronskian one, discontinuity at pi, but 2 degrees of freedom and 2 initials conditions means it's definitely unique. y=sinx was the explicit solution and as it's 0 at pi and so are y1 and y2, I think everything was fine (might be wrong though...)
Reply 12
I really don't have a clue...
Reply 13
Well, things go wrong at pi, so surely y=0 at pi (and in fact the wronskian's gonna be 0 for x=(2n+1)pi for all n so therefore y=0 at those points). Luckily y=sinx is 0 at x=(2n+1)pi so there isn't any problem, despite the potential discontinuity.
Makes sense but whatever, not worth losing the alpha over me thinks, 3 marks at the most...
Reply 14
Original post by tommm
I did all three probability questions except the volcano one, and I think I did two of them well, and the other I just struggled to find the mean with that binomial coefficient in it. Did you get 64/9 for the pea/mattress/prince question, and 51 (which, intuitively, seems unreasonably high) for the mean time to absorption?


64/9 - yes. Not sure which part you're talking about for the 51. I got the general formula QkQ_k := (E(time) at position k) = 10kk2210k - \frac{k^2}{2}, which is 0 at either end of the table (as it should be) and 50 at the centre, giving 25.5 in part d). (This comes from the difference equation Qk=Qk1+Qk+12+1Q_k = \frac{Q_{k-1} + Q_{k+1}}{2} + 1).
Reply 15
Original post by wooper
64/9 - yes. Not sure which part you're talking about for the 51. I got the general formula QkQ_k := (E(time) at position k) = 10kk2210k - \frac{k^2}{2}, which is 0 at either end of the table (as it should be) and 50 at the centre, giving 25.5 in part d). (This comes from the difference equation Qk=Qk1+Qk+12+1Q_k = \frac{Q_{k-1} + Q_{k+1}}{2} + 1).


I got that exact answer for the expected time, then checked over my work and realised I'd make a mistake when rearranging the difference equation, getting 1 instead of 2 on the RHS.
How come 2007 paper 3 (Groups & Vector Calculus), q7, asks for a proof of Green's theorem? Isn't that too long to do in a Section II question?

Are we supposed to reconstruct the long proof given in lectures, or do something clever using the first part of the question, about conservative vector fields?
Original post by stripy_and_nice
How come 2007 paper 3 (Groups & Vector Calculus), q7, asks for a proof of Green's theorem? Isn't that too long to do in a Section II question?

Are we supposed to reconstruct the long proof given in lectures, or do something clever using the first part of the question, about conservative vector fields?


Can you use Stokes' theorem to deduce it? I don't know the proof, but it seems a bit strange to have a short application bit in the first part then start the second with some tough bookwork.
Original post by Glutamic Acid
Can you use Stokes' theorem to deduce it? I don't know the proof, but it seems a bit strange to have a short application bit in the first part then start the second with some tough bookwork.

It's a puzzler - using Stokes's theorem to deduce it only takes a few lines, and then the whole question would take maybe 2/3 of a page, whereas proving it by the method used in lectures would take 2 whole pages by itself. I've no idea what they actually wanted! In the lectures, Stokes's theorem was proved using Green's theorem!

There doesn't seem to be a quick way of proving Green's theorem using the result of the first part either.
Reply 19
Original post by stripy_and_nice
It's a puzzler - using Stokes's theorem to deduce it only takes a few lines, and then the whole question would take maybe 2/3 of a page, whereas proving it by the method used in lectures would take 2 whole pages by itself. I've no idea what they actually wanted! In the lectures, Stokes's theorem was proved using Green's theorem!

There doesn't seem to be a quick way of proving Green's theorem using the result of the first part either.


At this stage in the game I don't think it's worth worrying about either way.

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