S2 exam official threadWatch
Just got back from my S2 exam, didnt find it too taxing so hopefully the UMS marks will come flying in! How did everyone else find it?
My recollection of exam:
1)a) Given R~B(15,0.3) -- find P(R=5) ... 0.2061 (2)
1)b) Given S~Po(7.5) -- find P(S=5) ... 0.1094 (1)
a)c) Given T~N(8,2^2) -- find P(T=5) ... 0 (1)
2)a)i) What is a population
2)a)ii) What is a Sample Frame (2)
2)b) Explain why sample frame != population (1)
2)c) Give an example with reason of Census & Sample(4)
3)a)Stick of length 2l is broken into two... define pdf of length of shorter half .
f(x) = 1/l for 0 < x < l // 0 otherwise (3)
3)b) P(X< l/3)... 1/3 (2)
3)c) E(X) ...... l/2 (1)
3)d) P(Both broken sticks being of length l/3)... (1/9) (2)
4)a) Give two additional conditions of binomial (2)
4)b) Perform hypothesis test with 1% significance level.. I remember I ended up doing normal distribution... 1 - phi(3.06)... interpolated as it wasn't in table got 0.011 - insignificant result. (6)
4)c) Commet on assumption... think this had to do with the interpolation .. think your ment to comment on that.. not sure (2)
5)a) Defecient article has probability of 0.032 ... so find probability of exactly two articles being defficient out of 10 articles... 0.0355 (3)
5)b) Sample size increased to 100 ... as n is large p is small... use poisson... 0.6025 (4)
5)c) Sample size increased further to 1000... approximate to poisson first with mean 32.. then approximate to normal... eventually got answer of 0.0294 (6)
6)a) Accidents on a particular stretch of road had mean of 3 per month, evaluate probability of there being more than 4 in a month... 0.1847 (3)
6)b) Probability of there being more than 4 in 3 months (I think)... 0.945 (2)
6)c) Do hypothesis test with 5% significance level to see if need speed regulation measures have made an impact given only 1 accident per month nor on average... 0.1991 > 0.05 -- so not sigificant. (4)
6)d) Do hypothesis test with 5% to see if new speed regulation has had an affect given only 55 accidents in 2 years... 0.0262 < 0.05 - significant result. (7)
7)a) Show k = 2/9 (3)
7)b) Find E(X) ... 2.5 (3)
7)c) Find Mode(X) ... 2.5 (2)
7)d) Find the CDF...
F(X) = 0 for x < 1 // (1/27)*(-2x^3 + 15x^2 -24x + 11) for 1 <= x <= 4 // 1 for x > 4 (5)
7)e) P(X <= 2.5) 0.5 (2)
7)f) Deduce Median... and comment on distribution... m = 2.5 as F(2.5) = 0.5 .. distribution is symmetrical. (2)
Absolutely loved question seven.. cos you could see where it was going.. and you knew it was right when it said "deduce the median.. and comment on the distribution"
[Edit]Marking scheme (given in red) should now be correct
[Edit2]Corrections made to Question 5 - thanks to the person who pointed them out.. don't know forum nick
it was so hard, i didnt finish in time lost the last last last part (2marks)
the first hypothesis i did but didnt really understand it.
also a lot of approximating, and the CDF.PDF question was complex and took quite a lot of working for each for such little marks.
and a tricky continuous uniform.
can anyone remember answers?
wasnt pleased, wanted to get 85% +, i got more like 65-75%!
oh well. please let june be much easier!!
np>5 and n(1-p)>5
Both of these were true i think so it was a perfectly acceptable assumption.
Man, I thought the exam was pretty annoying. Spent about 20 mins figuring out Q3, which I got right methinks. I thought it was a bit harsh how they stuck about 3 or 4 hypothesis tests in there. This paper was definetly a lot harder than I expected! Ah well.
I recollect most of those answers. I taught the whole module to myself in a month as time was pushed and the teachers couldnt teach it! Yesterday i did the last 8 exam papers and averaged 90% on them all so it should have gone ok!
how long did the 8 papers take to do??? j/w
I could do a paper an hour so it took me the whole day with breaks etc..... got my final exam tomorrow....PHYSICS.......the revision aint going too well!
I thought it was quite good, I finished with 40 mins left...I am quite pleased with myself actually, coz I taught S2 to myself...Started revising on Saturday when I found out I forgot to teach myself chpt 3 and 4...Spend like 4 hours revising for 3 days, and came out of exam feeling it was more than good...so~
Hey i see you too applied for Actuarial sci at LSE and MMORSE at warwick! Me too, i aint got offers either although i got a letter saying i was on the shortlist for LSE! I also got rejected from another course at LSE just like you. AND I TAUGHT S2 to myself........stange!
hopefully i got the same on my first attempt
save havin to do resit.
Hmm... i cant really see a concensus. Some ppl say it was hard, others say it was easy. I agree apart from Q3, which was worded differently. It was an easy paper. hopefully everybody else did really really badly and there will be low grade boundries.
i organised my time really badly and ended up missing out part of the last question
it didn't seem like a particularly hard paper, just loads to get through
oh well....there's always the resit
whoa~ freaky! what other subj did u apply for at LSE? I didn't get about shortlist for N321 though...quite worrying but hope i get a chance! Hey what subjects u doing for A-level?
I do Maths, Further Maths, Economics & Physics, got a high B in History last year too but dropped it.