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# S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST Tweet

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1. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
Going by Arsey's predictions... I scraped an A

I'll take that
2. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by und)
Did you make your method 100% clear eg. by drawing a tree diagram? If so then you definitely won't lose all the marks.
Yeah I drew a tree diagram, the same as the one before but with fading added onto the end, just with 0.5 instead of 0.05. Do you reckon I could get half marks for each question? (I.E 3/6 for both parts together).
3. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by Al04)
Okay there's 1 thing i don't understand.. the question that asks you to find the minimum thinning of the shell that results in death, given that pollutant levels above 16 are likely result in the death, how come you have to use 16 and not 17 in your regression line? Cause i thought about it during the exam, and it said pollutant levels above 16 result in death, so wouldn't you have to use 17?
I'm wondering the same thing
4. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by ArsLongaVitaBrevis)
Yeah I drew a tree diagram, the same as the one before but with fading added onto the end, just with 0.5 instead of 0.05. Do you reckon I could get half marks for each question? (I.E 3/6 for both parts together).
Yeah, you could probably get around half the marks. I definitely won't get anything for writing that P(B) and P(T) are independent and 'proving' that though...
5. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by AFC1993)
think i achieved 60/75
I hate s1...
Resitting this next year
Dude ....I'll be seein ya in the revision thread in January
6. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by Al04)
Okay there's 1 thing i don't understand.. the question that asks you to find the minimum thinning of the shell that results in death, given that pollutant levels above 16 are likely result in the death, how come you have to use 16 and not 17 as the value of p in your regression line? Since pollutant levels above 16 result in death, wouldn't you have to use 17?
p is a continuous variable so 'above' 16 is equivalent to 16 and higher.
7. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by und)
Yeah, you could probably get around half the marks. I definitely won't get anything for writing that P(B) and P(T) are independent and 'proving' that though...
wait if i subbed in the wrong value for the pmcc will i still get a mark for method?
8. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by und)
Yeah, you could probably get around half the marks. I definitely won't get anything for writing that P(B) and P(T) are independent and 'proving' that though...
Oh no! How did you manage that?
9. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by Arsey)
S1 May 2012

Not sure what to make of this paper, certainly required a little more thought than normal

Q1 - DRV

Easy

Q2 - PMCC

Easy

Q3 - Linear regression

Bit weird but pretty easy

Q4 - Venn

So stupidly easy

Q5 - Measures of location / spread

Very weird - you could have quite easily solved it by spotting that there were 22.5 5x5 squares so each 5x5 square represented 20 cars.

However I think this will be a massive bloodbath with many students picking up no marks.

Q6 - Normal distribution

Harder than normal I would say; I used the % points table to answer b) and c)

Q7 - Probability

Fairly easy but pretty unusual

I am going for

75 - 100ums
68 - 90ums
61 - 80ums
53 - 70ums
45 - 60ums
37 - 50ums
29 - 40ums

This thread will be locked at somepoint and then unlocked at midnight following the Stats 1 examination.

I will upload the paper and my solutions to this post.

I will do my best to answer questions about the paper but please try to read the thread first so that I am not answering the same questions lots of times.

Here are some links to previous S1 threads, they are worth a read and you will see what the common errors were...

S1 Jan 2012 - http://www.thestudentroom.co.uk/show....php?t=1865940

S1 June 2011 - http://www.thestudentroom.co.uk/show....php?t=1619124

The second link contains loads of past papers, model answers etc

Good luck.
Thanks a bunch for the mark scheme!!!!

only a few questions:
For 3B) does you think they'll accept - there is strong positive correlation
For 5A) i got the same answer but working was very different (sort of)
E.g. i work out area under graph in terms of x to get 112.5x, then divided the total 450 by this to get 4 for each square, then area of those above 35, would i still get full marks?
For 6c) i might have used women's SD when you had to use men's SD, how many marks would i lose?

Thanks, much appreciated
10. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
Ran out of time when I realised how the histogram is done goodbye A
11. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by Al04)
Okay there's 1 thing i don't understand.. the question that asks you to find the minimum thinning of the shell that results in death, given that pollutant levels above 16 are likely result in the death, how come you have to use 16 and not 17 in your regression line? Cause i thought about it during the exam, and it said pollutant levels above 16 result in death, so wouldn't you have to use 17?
I'm wondering the same thing
(Original post by pjanoo)
I'm wondering the same thing
Definitely 16. You could argue that at 16.0000001, and so on is the point at which it is above 16 and therefore will cause the death at that moment, so as it is so close to 16, you would simply just take it as 16. They may give you the marks for 17 though, who knows.
12. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by pjanoo)
hey, could someone explain why the value used in the regression line in 3f is 16 and not 17? I'm not denying that it's right, I'm just confused as the question said pollution levels above 16 are likely to result in death so to find the minimum thinning of a shell, why would we use 16 if it's levels above 16 that are likely?
I was wondering the same thing.
13. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by und)
p is a continuous variable so 'above' 16 is equivalent to 16 and higher.
this is most probably a silly question, sorry, but does that mean I wouldn't get the mark for 17?
14. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
Now I feel even less confident about what I got
15. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by ArsLongaVitaBrevis)
Oh no! How did you manage that?
I didn't revise much (I know it's not really an excuse) so in the rush of the exam I thought that P(BnT)=P(B)P(T|B) implied that they're independent which is obviously nonsense.
16. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by Jammy4410)
Thanks a bunch for the mark scheme!!!!

only a few questions:
For 3B) does you think they'll accept - there is strong positive correlation
For 5A) i got the same answer but working was very different (sort of)
E.g. i work out area under graph in terms of x to get 112.5x, then divided the total 450 by this to get 4 for each square, then area of those above 35, would i still get full marks?
For 6c) i might have used women's SD when you had to use men's SD, how many marks would i lose?

Thanks, much appreciated
i did 5A same way as you, we should get full marks still
17. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by James-Lloyd)
Definitely 16. You could argue that at 16.0000001, and so on is the point at which it is above 16 and therefore will cause the death at that moment, so as it is so close to 16, you would simply just take it as 16. They may give you the marks for 17 though, who knows.
18. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by yaboy)
wait if i subbed in the wrong value for the pmcc will i still get a mark for method?
Where did you have to sub in the pmcc?
19. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
(Original post by koolkid1011)
Hey two questions, if anyone can answer i'd appreciate it a lot:

1. For question 4a i gave two examples which were (B n W) and (T n W) . Each one is correct but would i be marked down for giving two? i got the explanation correct btw...

2. For question 5e would i get away by saying that the data is almost symmetrical and therefore it would be appropriate to use the mean? Also for question 5d i said the distribution was symmetrical for the same reasons above, again would i get the marks?

Thank you
4a - clearly that is fine

5e - yeah prob, i thought it was odd that it was quite close to being symmetrical.
20. Re: S1 May 2012 - Post Exam Thread - Paper and Solutions in the FIRST POST
What would 67/75 be? I messed up on question 6 -_- !!!!
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