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Edexcel S3 - Wednesday 25th May AM 2016

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Original post by Zacken
Generally, if it's not too much trouble, I would do it both ways to make sure my answer is correct. (they amount to the same thing, although a bit of care has to be taken w.r.t decimal places rounding) If it was an annoying calculation where the class was >= 6 and I'd need to look up cumulative crap in the tables, then I'd just add up the previous ones and do total - (sum of previous).

Actually, that makes sense. Cuz that question I did before (where the mark scheme did the adding up method), I remember it being a class like >=6. So definitely the mark scheme agrees with you. Thanks!
Original post by Geraer1
Okay thanks! And in this paper, actually one part of q6 involves pooling two columns together as one of the expected frequencies is below 5 for a contingency table. So it did appear in a paper!:smile:

Original post by Zacken
Yes, June 15. You had to explain why, but you didn't actually have to combine it yourself which was what I was talking about.
Yeah, someone brought that up yesterday. :tongue:
Original post by Zacken
Yeah, someone brought that up yesterday. :tongue:


Ah okay!:biggrin:
Reply 903
Avatar for Rkai01
Rkai01
6
Original post by Music With Rocks
Is there ever a time in S3 when you would use the σ2 rather than S2 formula?


What is the σ2 formula?
Reply 904
Avatar for zaybun
zaybun
2
Quick question:

You must combine classes for continuous uniform if E is less than 5, right?

(I know that the same goes for all other chi-sqaured tests)
Original post by zaybun
When they ask you to calculate the biased variance as opposed to the unbiased one I'm guessing.


Anything can be a biased estimator of variance.

Original post by Rkai01
Could we actually be asked to calculate c in a pdf and those type questions?

I can't remember much of those s2 things


Yes, they certainly could but most likely wouldn't given the repetitive nature/style of S3 past papers.
Original post by physicsmaths
+-0.6mm so the modulus of the difference.
This is very known and comes up tonnes go over it in the book.


when was that paper?
Original post by zaybun
Quick question:

You must combine classes for continuous uniform if E is less than 5, right?

(I know that the same goes for all other chi-sqaured tests)


Yes.
Reply 908
Avatar for zaybun
zaybun
2
Original post by Zacken
Yes.


Thank you! Teacher did an example months back and I just had a look through my notes and I guess she forgot to combine the classes :s-smilie:
Original post by tazza ma razza
when was that paper?


2011 or 2010 not sure.


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Original post by physicsmaths
2011 or 2010 not sure.


Posted from TSR Mobile


(Y)
Original post by tazza ma razza
when was that paper?


June 2010, iirc.

Original post by zaybun
Thank you! Teacher did an example months back and I just had a look through my notes and I guess she forgot to combine the classes :s-smilie:


Yep, must be.
Has anyone got a link to last years paper?
Original post by Messier31
Has anyone got a link to last years paper?


Check the Edexcel website
Original post by Messier31
Has anyone got a link to last years paper?


Im about to do that one aswell.
Report back in abit.


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Original post by tazza ma razza
(Y)


?


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Original post by Euclidean
Check the Edexcel website


Oh :colondollar:

Thanks

Original post by physicsmaths
Im about to do that one aswell.
Report back in abit.


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I'll be expecting you in about half an hour :lol:
Original post by physicsmaths


*thumbs up*
Original post by physicsmaths


(Y) is a thumbs up emoji, probably not what you think :tongue:
Original post by Euclidean
(Y) is a thumbs up emoji, probably not what you think :tongue:


My thoughts exactly when I first came across it. :mmm:

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