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Edexcel S3 - Wednesday 25th May AM 2016

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Original post by econam
Im also confused by this. I thought because U1 U2... were all independant of each other then you don't square the constant of variation? Why is it not just over 5?


Var(4U1)=16Var(U1)Var(4U_1) = 16Var(U_1)

Var(Ui5)=125Var(Ui)Var(\frac{U_i}{5}) = \frac{1}{25}Var(U_i)

Is it the movement from the whole Var function to individuals which has confused you?
Original post by SeanFM
Disagree :tongue: what other exam do you get such lovely prose? :tongue: except maybe those series questions in C1/C2.


lol.
M4-5 STEP and olympiads are enjoyable. step stats is enjoyable but s3 no way.
this is how **** stats is, ch5 can be taught to an S1 candidate in 5 minutes.
Original post by physicsmaths
i keep on applying the 0.5 **** since thats what the book did in examples.


I did minimal questions from the book :biggrin:

I think the S3 book is s***, no way around it

Original post by connorbarr
sound thanks, so i should do it for continuous uniform as well if there are gaps?


Yup :smile:
Original post by Euclidean
I did minimal questions from the book :biggrin:

I think the S3 book is s***, no way around it



Yup :smile:

thanks a lot
Original post by Euclidean
I did minimal questions from the book :biggrin:

I think the S3 book is s***, no way around it



Yup :smile:


so if i did a test of model suitable for normal and gaps were lets say
5- 7 8-9 10-12 i wouldnt make them 7.5-9.5 etc?
s3 june 15 is 'fair' my ass
Original post by physicsmaths
so if i did a test of model suitable for normal and gaps were lets say
5- 7 8-9 10-12 i wouldnt make them 7.5-9.5 etc?


edit: sorry I didn't see the 'wouldn't'

You would apply a continuity correction because you're approximating something which is discrete (I presume?) by a distribution which is continuous

@physicsmaths
(edited 7 years ago)
Is there an s3 paper from jan 16 IAL? The only IAL papers I can find are June 14 and June 15.

Also, is there a June 13 Withdrawn?
Original post by AmarPatel98
s3 june 15 is 'fair' my ass


Did you get Var(U1−Uˉ)Var(U_1 - \bar{U})? :tongue:

Original post by AmarPatel98
Is there an s3 paper from jan 16 IAL? The only IAL papers I can find are June 14 and June 15.Also, is there a June 13 Withdrawn?


Don't think so
Original post by physicsmaths
lol.
M4-5 STEP and olympiads are enjoyable. step stats is enjoyable but s3 no way.
this is how **** stats is, ch5 can be taught to an S1 candidate in 5 minutes.


i did OCR maths so i did ch5 in S1
Original post by Euclidean
edit: sorry I didn't see the 'wouldn't'

You would apply a continuity correction because you're approximating something which is discrete (I presume?) by a distribution which is continuous

@physicsmaths


indeed so what were you saying you shouldn't do ?
Has anyone got a link for the June 15 IAL mark scheme? Cheers
Original post by Zacken
Yep.


You could 'assume' that the sample is large enough for the CLT to be accurate enough to implement?
Original post by Euclidean
Did you get Var(U1−Uˉ)Var(U_1 - \bar{U})? :tongue:



Don't think so


Hell no but ngl i thought it was a nice question, so if they throw it as us again, we're ready!
Original post by Nikhilm
You could 'assume' that the sample is large enough for the CLT to be accurate enough to implement?


No, if n≥50n \geq 50, then CLT is invoked. If the question says n=70n = 70, then you don't "assume 70 > 50", do you?

Original post by physicsmaths
so if i did a test of model suitable for normal and gaps were lets say
5- 7 8-9 10-12 i wouldnt make them 7.5-9.5 etc?


Original post by Euclidean
edit: sorry I didn't see the 'wouldn't'

You would apply a continuity correction because you're approximating something which is discrete (I presume?) by a distribution which is continuous

@physicsmaths


You would make them 7.5 - 9.5.

Original post by AmarPatel98
s3 june 15 is 'fair' my ass


It is. What did you dislike about it?
Original post by ChrisP97
Has anyone got a link for the June 15 IAL mark scheme? Cheers


It's on the Edexcel website, just navigate through: our quals -> internationa a-levels -> mathematics -> exam materials -> S3
Original post by AmarPatel98
s3 june 15 is 'fair' my ass


What's unfair about it?
Original post by Euclidean
Var(4U1)=16Var(U1)Var(4U_1) = 16Var(U_1)

Var(Ui5)=125Var(Ui)Var(\frac{U_i}{5}) = \frac{1}{25}Var(U_i)

Is it the movement from the whole Var function to individuals which has confused you?


Had a look at the mark scheme - I feel I understand it now. Combining 4U1 the get 16sigma
Reply 738
Avatar for kennz
kennz
8
Its actually this for normal distribution chi squared tests if you refer to the book.
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Original post by kennz
Its actually this for normal distribution chi squared tests if you refer to the book.


If it's a normal distribution then the greater than or equal to or w/e doesn't make a difference.

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