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# Edexcel S3 - Wednesday 25th May AM 2016 watch

1. (Original post by Euclidean)
I wanted to do a couple more papers today, finished 2011 just.

But it's probably one of the most boring things I've ever done

You expecting a 75/75 in S3? I think silly mistakes might just get me like using variance instead of standard deviation
Tbh I think the textbook has a couple of really good questions. I'm planning to do a few from that and then memorise mark schemes. I have mixed opinions - on one hand the combination of RVs and estimator stuff can be nice but other things are just...

I'm hoping for 95 UMS. My M3 was not as decent as I hoped because like an idiot, I lost a factor of pi somewhere. I'm gonna spend a decent amount of time actually reading the questions so that I don't throw away marks in the comments.

Looks like you've come a long way for someone starting the module only a couple of days back.
2. (Original post by physicsmaths)
By Tied ranks we mean two values are the same?
? So PMCC tests doesn't come up in papers? Just spearmans using the two different formulas?

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so if you have 2 values the same before u rank them, since they are the same they will have the same rank, at which point use PMCC formula, i remember a question said once 'the examiner got this value wrong and it was in fact 54, what happens to the ranks now' or something, and there was already a 54 in the tables, it was 1 mark just say tied ranks so use Sxx, Syy etc.
3. (Original post by Ayman!)
Tbh I think the textbook has a couple of really good questions. I'm planning to do a few from that and then memorise mark schemes. I have mixed opinions - on one hand the combination of RVs and estimator stuff can be nice but other things are just...
That's a good shout. I'll probably look at the small markers like reasons for using PMCC/SRCC, sampling and now I'm just writing out 'Explain what you understand by the Central Limit Theorem' a tonne of times to make sure I can remember it

(Original post by Ayman!)
Looks like you've come a long way for someone starting the module only a couple of days back.
Past papers are the fastest method of studying if you take the time to mark them properly, skimming the module and then blasting all the papers out

(Original post by Ayman!)
I'm hoping for 95 UMS. My M3 was not as decent as I hoped because like an idiot, I lost a factor of pi somewhere. I'm gonna spend a decent amount of time actually reading the questions so that I don't throw away marks in the comments.
S3 could be a 75 for me but it probably won't be, boundaries are nearly always steep (even for 15 UK) and I'm likely to make mistakes on comments and silly things like that too
4. before june 15, was getting 67+/75... hoping that something good comes up
5. (Original post by tazza ma razza)
acc + fin
Good luck, hope you get in!
6. Please could anyone clarify when we quote the parameters and n,p etc in hypotheses for goodness of fit and when we don't? Thanks
7. (Original post by Nikhilm)
No I mean calculating CI for pop. mean with s within the standard error as opposed sigma. if n is large then sample variance = sample pop, so I'm asking that could the s instead of sigma be used in a CI for pop mean?
I don't quite understand but there has never been a question where the variance is s^2 in seed of sigma^2 and they've then asked to calculate the CI so i doubt it'll come up.
8. (Original post by economicss)
Please could anyone clarify when we quote the parameters and n,p etc in hypotheses for goodness of fit and when we don't? Thanks
was meantioned 2 pages ago i think
9. Question 4
A random sample of the members of a club is to be asked for their approval on a
certain club matter.
The secretary asks n club members, n > 50 , of whom a proportion of 0.7 gives their
approval on the matter.
A 99% confidence interval for the proportion of members approving the club matter
is found not to contain 0.85.
Determine the least value of n .

uhhhh a leel help pls? (s/o anyone who gets the leel reference)
10. (Original post by Zacken)
You include them if they're assumed and you don't include them if you calculate it from the observed data.
So if we have to show a probability is 0.3 for example, then we wouldn't include this in the hypotheses and we would just say 'binomial distribution is a suitable fit' but if we were explicitly told 'the teacher thinks the distribution can be modelled by B(20,0.05) for example then we would write B(20,0.05) in the hypotheses, is that right?Thanks
11. (Original post by tazza ma razza)
was meantioned 2 pages ago i think
Thanks
12. (Original post by tazza ma razza)
Question 4
A random sample of the members of a club is to be asked for their approval on a
certain club matter.
The secretary asks n club members, n > 50 , of whom a proportion of 0.7 gives their
approval on the matter.
A 99% confidence interval for the proportion of members approving the club matter
is found not to contain 0.85.
Determine the least value of n .

uhhhh a leel help pls?
Where is this question from?
13. (Original post by coolguy123456)
Where is this question from?
http://www.madasmaths.com/archive/ma...on_samples.pdf last qn at end of the doc

14. Does anyone have any ideas for part c? Much appreciated
15. (Original post by coolguy123456)
Where is this question from?
i got the opposite tail (?) and hence the wrong value of n
16. (Original post by econam)

Does anyone have any ideas for part c? Much appreciated
think about varience and fractions + you should get it
17. (Original post by tazza ma razza)
Question 4
A random sample of the members of a club is to be asked for their approval on a
certain club matter.
The secretary asks n club members, n > 50 , of whom a proportion of 0.7 gives their
approval on the matter.
A 99% confidence interval for the proportion of members approving the club matter
is found not to contain 0.85.
Determine the least value of n .

uhhhh a leel help pls? (s/o anyone who gets the leel reference)
lol i'm stuck on this one since yesterday, i get that in the mark scheme, he use binomial and use the variance formula np(1-p) to estimate the variance of a normal distribution but the n was gone some where ._.
18. (Original post by anndz3007)
lol i'm stuck on this one since yesterday, i get that in the mark scheme, he use binomial and use the variance formula np(1-p) to estimate the variance of a normal distribution but the n was gone some where ._.
yh i got the np(1-P) and then i didn't get the bit about less than 0.85 or more than 0.85 (ie less than 0.15) i used less than as it is a normal curve and 0.85 wasn't in range so it must be less than and so got the wrong value of n
19. (Original post by tazza ma razza)
Question 4
A random sample of the members of a club is to be asked for their approval on a
certain club matter.
The secretary asks n club members, n > 50 , of whom a proportion of 0.7 gives their
approval on the matter.
A 99% confidence interval for the proportion of members approving the club matter
is found not to contain 0.85.
Determine the least value of n .

uhhhh a leel help pls? (s/o anyone who gets the leel reference)
we're not required to calculate CI for proportion.
20. (Original post by Nikhilm)
we're not required to calculate CI for proportion.
you sure?

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