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Edexcel June 2013 (R) S1 Paper help needed! Q5d,e

I really need help with question d and e as I don't understand how to do the question and what it means. Someone please help me!

Here's the link of the question:
https://i.gyazo.com/2ff17625562a5aa3d632fe99e29ca3b4.png

(edited 7 years ago)
2ff17625562a5aa3d632fe99e29ca3b4.png224.5KB
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Susta1nz
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Bump ,please someone help!
Ah! THE turner question!
Calculate the new mean, see how that affects the definition they've given.
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Susta1nz
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Original post by Mr T Pities You
Ah! THE turner question!
Calculate the new mean, see how that affects the definition they've given.


The new mean is the same as the old mean, however how does that affect Sxx?
Original post by Susta1nz
The new mean is the same as the old mean, however how does that affect Sxx?


Use their definition.
The old Sxx was found by adding up the (x-xbar)^2 terms
Your new Sxx will add in a new (x-xbar)^2 term. The new x value is 6, and the new xbar is 6, so the new term added in is zero squared. So the new Sxx is the same as the old one.
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Susta1nz
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Original post by Mr T Pities You
Use their definition.
The old Sxx was found by adding up the (x-xbar)^2 terms
Your new Sxx will add in a new (x-xbar)^2 term. The new x value is 6, and the new xbar is 6, so the new term added in is zero squared. So the new Sxx is the same as the old one.


Ohh, thanks! But what I'm also confused about is how do you know you add that value? I thought it meant the new Sxx value is Sxx= (THEIR DEFINITION). It doesn't make it very clear...
Original post by Susta1nz
Ohh, thanks! But what I'm also confused about is how do you know you add that value? I thought it meant the new Sxx value is Sxx= (THEIR DEFINITION). It doesn't make it very clear...


The sigma implies the adding.
It's a tricky and unusual question and my classes this year have both asked about it - I hope your teacher brought it to your attention!
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Susta1nz
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Original post by Mr T Pities You
The sigma implies the adding.
It's a tricky and unusual question and my classes this year have both asked about it - I hope your teacher brought it to your attention!


Oh, I thought the sigma meant the sum of. My teacher may have missed it or maybe I did
Original post by Susta1nz
Oh, I thought the sigma meant the sum of. My teacher may have missed it or maybe I did


It does, and sum means adding!
Good luck tomorrow.
Reply 9
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Susta1nz
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Original post by Mr T Pities You
It does, and sum means adding!
Good luck tomorrow.


Ah, this still confuses me as I don't get the same number for Sxx :'(

Thank you so much for the help though!
How do you send pictures I can show you my working, but I'm not sure if it's how you would do it but it still works
(edited 7 years ago)
image.jpg
image.jpg
Hope this helps

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