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S2 18th January 2013

Should still get the marks :smile:

More often than not they put in the alternate mark scheme that getting the right answer w/o working scores all the marks...

Not always, but this seems like one they might do that for

Cool thanks for your help :smile:

fingers crossed

Reply 741

Wa 007

2

What do you guys reckon the grade boundaries for an A and A will be 64 and 69?

Reply 742

username937760

16

Original post by S2 sucks eggs

Even if i got the wrong answer for part e? ( i got 8/13 which was right for my pdf but wrong for the correct pdf). I will be very happy if i do get all the marks for that, I didnt know error carried forward could do that!

I think I'm confused by your working.

If you worked out Var(Y) correctly but re-arranged the formula instead of integrating to find E(Y^2) then you would lose all the marks for part d) but gain all the marks for e). If your variance is wrong then you would lose marks for e) as well.

Original post by Wa 007

What do you guys reckon the grade boundaries for an A and A will be 64 and 69?

My teacher expects 67ish for an A*.

@xxZazxx: Sorry, that sounds fine. I didn't have a 15 anywhere as I multiplied the equation by 20 and subtracted to get A on its own first instead of getting B on its own. Either way is fine though.

Reply 743

Wa 007

2

Original post by DJMayes

I think I'm confused by your working.

If you worked out Var(Y) correctly but re-arranged the formula instead of integrating to find E(Y^2) then you would lose all the marks for part d) but gain all the marks for e). If your variance is wrong then you would lose marks for e) as well.

My teacher expects 67ish for an A*.

@xxZazxx: Sorry, that sounds fine. I didn't have a 15 anywhere as I multiplied the equation by 20 and subtracted to get A on its own first instead of getting B on its own. Either way is fine though.

Right thanks and sorry to keep repeating myself but would i lose any marks if i did a one tail hypothesis test?

Reply 744

S2 sucks eggs

(Originally Posted by DJMayes)
part d) explicitly said "Use integration to show that

" so if you haven't used integration I don't think you'll get any marks for it - as it was a "show that" question you aren't likely to get a mark for reaching the final answer another way either. You should have picked up all the marks for part e) though.

Even if i got the wrong answer for part e? ( i got 8/13 which was right for my pdf but wrong for the correct pdf). I will be very happy if i do get all the marks for that, I didnt know error carried forward could do that!

Reply 745

LShirley95

Original post by Wa 007

Right thanks and sorry to keep repeating myself but would i lose any marks if i did a one tail hypothesis test?

I did a one tailed test. I don't see the problem with it, seeming as we already knew the test was a less than test.

Reply 746

savchristou

any chance of attaching the S2 paper?

Reply 747

username937760

16

Original post by LShirley95

I did a one tailed test. I don't see the problem with it, seeming as we already knew the test was a less than test.

We technically didn't - the exact wording was "(c) Test at the 5% level of significance whether or not the opinion poll provides evidence
to support Mrs George’s claim." As it didn't specify that the proportion of votes is greater/less than her claim, it can easily be interpreted as a two-tailed test, even though realistically you're only interested in whether it's less than. I personally used a two-tailed test, but I think it's highly likely that both one and two tailed tests will be allowed as the question didn't make it clear which.

Reply 748

S2 sucks eggs

(Originally Posted by DJMayes)
part d) explicitly said "Use integration to show that

" so if you haven't used integration I don't think you'll get any marks for it - as it was a "show that" question you aren't likely to get a mark for reaching the final answer another way either. You should have picked up all the marks for part e) though.

Even if i got the wrong answer for part e? ( i got 8/13 which was right for my pdf but wrong for the correct pdf). I will be very happy if i do get all the marks for that, I didnt know error carried forward could do that!

Reply 749

LShirley95

Original post by DJMayes

We technically didn't - the exact wording was "(c) Test at the 5% level of significance whether or not the opinion poll provides evidence
to support Mrs George’s claim." As it didn't specify that the proportion of votes is greater/less than her claim, it can easily be interpreted as a two-tailed test, even though realistically you're only interested in whether it's less than. I personally used a two-tailed test, but I think it's highly likely that both one and two tailed tests will be allowed as the question didn't make it clear which.

I would think they would both be fine, yes. Looking at old mark schemes sometimes they allow both even when it was blatantly obvious which one to use.

Reply 750

Wa 007

2

Original post by LShirley95

I would think they would both be fine, yes. Looking at old mark schemes sometimes they allow both even when it was blatantly obvious which one to use.

Ah okay thanks :smile:

Reply 751

koolkid1011

was wondering what everyone else put for their definition of a hypothesis? never had to define that before...

Reply 752

S2 sucks eggs

(Originally Posted by DJMayes)
part d) explicitly said "Use integration to show that

" so if you haven't used integration I don't think you'll get any marks for it - as it was a "show that" question you aren't likely to get a mark for reaching the final answer another way either. You should have picked up all the marks for part e) though.

Even if i got the wrong answer for part e? ( i got 8/13 which was right for my pdf but wrong for the correct pdf). I will be very happy if i do get all the marks for that, I didnt know error carried forward could do that!

Reply 753

DO123

Just wondering if anyone is going to upload the mark scheme or at least the paper so together we could answer it and upload so everyone knows?

Reply 754

iElio

The mosquito question was the question that caught me out, along with hypothesis definition. For the conditional probability I got 304/529 which judging by what people have said on here, it is wrong. Also for the number of days I did 1-225/(x+15)^2 so ended up getting that wrong, and to make things worse I then made it equal to 0.09 instead of 0.9 after taking the 1 over..... So I ended up with an answer of 35. Not sure how many marks the two parts will cost me out of 7, hopefully not 7!

This was posted from The Student Room's iPhone/iPad App

(edited 11 years ago)

Reply 755

yaboy

Original post by DJMayes

We technically didn't - the exact wording was "(c) Test at the 5% level of significance whether or not the opinion poll provides evidence
to support Mrs George’s claim." As it didn't specify that the proportion of votes is greater/less than her claim, it can easily be interpreted as a two-tailed test, even though realistically you're only interested in whether it's less than. I personally used a two-tailed test, but I think it's highly likely that both one and two tailed tests will be allowed as the question didn't make it clear which.

ive seen questions like this in past s2 paper but i just dont understand which one they actually want because usually they state use a two tailed test at 2.5% or something i did a 1 tailed test and got CR<4 so h0 was accepted and mr georges claim was supported by evidence but no idea if it was right

Reply 756

username937760

16

Original post by DO123

Just wondering if anyone is going to upload the mark scheme or at least the paper so together we could answer it and upload so everyone knows?

If you check page 26/27 my answers are uploaded. They're not a mark scheme but they're mostly agreed upon barring the hypothesis definition.

Reply 757

study beats

22

How the hell do you do the damn mosquito question

Reply 758

Jackfinance17

3

I got a = 24/27 which is 8/9... does that mean I lose 1 mark for not simplifying the answer?

Also I put the hypothesis defo as "a parameter in a statistical data that is assumed to be correct... a parameter someone claimed to be correct..." since it is hypothesis not hypothesis test... or null or alternative hypothesis... isn't hypothesis is same as null hypothesis in terms of the surface meaning of the word.

Reply 759

01nathan

Does anyone have a PDF of the S2 Paper, there is huge demand for it on here?

S2 18th January 2013

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