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Edexcel S1 - 15th June, 2016 [Exam Discussion]

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can anyone link the 2016 ial w/model answers pls? Thanks!
Original post by HK4
For normal distribution is the middle line/axis the mean? So its usually 0 but for Z it would be the mean??


The x axis are the values that the distributions take. (for Z, the 'centre' is indeed 0, and the probability of values lying in either half is 0.5). For other distrubtions, the 'middle line' you describe is the mean, yes.

and the y axis is the probability of an individual point occuring but that's not so relevant (so you can see that the mean is the most probable value that the distribution would take, and then as you move further away the chances of those further values occuring decreases.
Original post by Uberphuq
Are you 100% sure?

Because I really am unsure and don't want this to cost me marks haha....


This is how I remember it matey, and I'm sure this works.

Just always use N/2. Avoid getting confused.
For Discrete, use N/4, N/2 and 3N/4. If you get a decimal place as your result, ROUND UP to the nearest integer. If you get an integer as your result, TAKE THE AVERAGE of that value and the next value.
For Continuous, just use N/4, N/2 and 3N/4 standard - then interpolate.

That's how I remember. You can use N+1/2, but it's a different rule which for me makes it more confusing.
Good luck everyone :h: I'm done for the day. Just try your best :wink:
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civ1
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https://1a388b28f5ce9318f837a64962fc3ceab9c61da8.googledrive.com/host/0B1ZiqBksUHNYU2s1SVY1VDN2Q0U/June%202015%20(IAL)%20MA%20-%20S1%20Edexcel.pdf

How do you do 8D
can anyone plzzzzz tel me da points to write wen comparin graphs such as box plots
i know we shuld write about measure n spread of location bt i get mixed up as sometimes its median n iqr n other times its range and mean
how would coding affect the value of Sxx, Syy and Sxy, i saw one question on the Gold paper asking about it, even i answer it right, it was kind of a good guess though ...
Original post by hogree
This is how I remember it matey, and I'm sure this works.

Just always use N/2. Avoid getting confused.
For Discrete, use N/4, N/2 and 3N/4. If you get a decimal place as your result, ROUND UP to the nearest integer. If you get an integer as your result, TAKE THE AVERAGE of that value and the next value.
For Continuous, just use N/4, N/2 and 3N/4 standard - then interpolate.

That's how I remember. You can use N+1/2, but it's a different rule which for me makes it more confusing.


youdaman
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Mina_
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Screenshot 2016-06-14 21.04.59.png

Can someone explain (e) ? Where the mean is 10.8 and SD is 7.46
Original post by saitama kun
can anyone plzzzzz tel me da points to write wen comparin graphs such as box plots
i know we shuld write about measure n spread of location bt i get mixed up as sometimes its median n iqr n other times its range and mean


One measure of location (from box plots the median)
On measure of spread (range or IQR for box plots)
And I think also skewness (Q2-Q1<Q3-Q2 positive Q2-Q1>Q3-Q2 negative)
Original post by hogree
This is how I remember it matey, and I'm sure this works.

Just always use N/2. Avoid getting confused.
For Discrete, use N/4, N/2 and 3N/4. If you get a decimal place as your result, ROUND UP to the nearest integer. If you get an integer as your result, TAKE THE AVERAGE of that value and the next value.
For Continuous, just use N/4, N/2 and 3N/4 standard - then interpolate.

That's how I remember. You can use N+1/2, but it's a different rule which for me makes it more confusing.


Wait, so.. If I get an integer, say 15, and the next number is 16, my quartile will be 15.5?
Original post by MMMSS
Ok so it's a matter of substitution- youve been given the codes for x and y

so instead of y=0.746+0.102x,
you will now get v/100,000 = 0.746 + 0.102*(s-50/10)

then simplify:
v= 23600 + 1020 s

ergo, d= 1020


Thank you. Good luck for the exam ☺
Original post by anndz3007
how would coding affect the value of Sxx, Syy and Sxy, i saw one question on the Gold paper asking about it, even i answer it right, it was kind of a good guess though ...


mate - this has been asked countless times - I can't recollect there being an answer tho ahaha Have you checked the textbook?
Original post by civ1


Work out the Midpoints, Work out the Frequency with the Frequency Density, then Multiply your Frequency and Midpoint Values before Adding the Sum. The model answers have the method at the bottom of the last left page.
Original post by civ1


Area x Frequency
Original post by Uberphuq
Wait, so.. If I get an integer, say 15, and the next number is 16, my quartile will be 15.5?


So, say you have 60 values. You want to work out the lower quartile. Do n/4 ---> 6/4 -----> 15. So you use the 15.5th value.
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Mina_
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Original post by thelegend99
can anyone link the 2016 ial w/model answers pls? Thanks!


Type in Jan 2016 IAL tsr on Google and a download link should come up
Original post by hogree
So, say you have 60 values. You want to work out the lower quartile. Do n/4 ---> 6/4 -----> 15. So you use the 15.5th value.


and this would be done on say a stem and leaf diagram?
Original post by anndz3007
how would coding affect the value of Sxx, Syy and Sxy, i saw one question on the Gold paper asking about it, even i answer it right, it was kind of a good guess though ...


So, if you have a Coding where of say 2X+6, you ignore the +6. You multiply the Sxx by 4 (because that's 2^2), You multiply the Sxy by 2, and you don't multiply the Syy. That's what I saw from someone else. PMCC remains the same always.

Original post by tazza ma razza
and this would be done on say a stem and leaf diagram?

Yes, that would be an example of when you would use that method.
Original post by Mina_
Type in Jan 2016 IAL tsr on Google and a download link should come up


thanks

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