You are Here: Home >< Maths

# Edexcel S3 - Wednesday 25th May AM 2016 watch

Announcements
1. (Original post by Geraer1)
Spearman rank correlation coefficient, when ranking the values, if you rank biggest value of x, 1 and smallest 10, then you do the same for y even if it gives you a negative value which means a negative correlation?
Correct.

Haha, no problem! I fully understand the independence thing now, thank you. If only the textbook was as clear as your description lol.
Thank you!
2. (Original post by anndz3007)
just run through my note on significant testing and i wrote " for PMCC, variables have to follow normal distribution", and i have no idea what this mean and how this applies ..........
It just means that if you want to use the pmcc, you have to assume that "the data is distributed bivariately normal". No point understanding it at this point, just memorise it and write it in the exam if they ask you "what assumption did you make for pmcc?"
3. (Original post by Zacken)
Correct.
Okay, thanks!
4. Banging.
Bye guys, managed a whopping 2 n 1/2 papers todays when my expected fequency was 6.
Good luck people, remember that the mean is the sum of loads of things divided by how many things you got.

Posted from TSR Mobile
5. (Original post by Zacken)
It just means that if you want to use the pmcc, you have to assume that "the data is distributed bivariately normal". No point understanding it at this point, just memorise it and write it in the exam if they ask you "what assumption did you make for pmcc?"
wow thank you, imagine if this question actually comes up tmr lol
6. (Original post by anndz3007)
wow thank you, imagine if this question actually comes up tmr lol
Wouldn't be surprised, I just hope quota sampling doesn't come up.
7. What is a mean?
8. (Original post by Zacken)
Wouldn't be surprised, I just hope quota sampling doesn't come up.
I'm getting quite good at the sampling methods actually, my teacher trained us by making us do the bloody long aqa questions where i literally got 0/9 the first time i did it lol.
actually i realised that the question about primary and secondary data never came up before, the book specify that we need to know about it
9. (Original post by anndz3007)
I'm getting quite good at the sampling methods actually, my teacher trained us by making us do the bloody long aqa questions where i literally got 0/9 the first time i did it lol.
actually i realised that the question about primary and secondary data never came up before, the book specify that we need to know about it
I remember primary/secondary **** from my business GCSE lol I'll be able to blag my way through.
10. (Original post by econam)
What is a mean?
The middle.
11. (Original post by Zacken)
I remember primary/secondary **** from my business GCSE lol I'll be able to blag my way through.
lol I did so bad at Business Studies that i decided to give up my dream on being the second Bill Gate.
Anyway, thank you for your help today, im gonna sleep early, goodluck tmr !!
12. (Original post by anndz3007)
lol I did so bad at Business Studies that i decided to give up my dream on being the second Bill Gate.
Anyway, thank you for your help today, im gonna sleep early, goodluck tmr !!
Good idea, it's already 2 a.m here and I have to wake up in 6 hours lol fml.

Thank you.
13. (Original post by Zacken)
Putting it up here for you, hope you don't mind:
Thanks so much guys
14. Really confused about something guys!!Uno when u use contingency tables for chi squared u do (row-1)(column-1) to get degrees of freedom- if you then pool/combine a row (frequencies<5) do u take 1 away from the value of v?I.e. (3-1)(2-1)-1?Thanks!!
15. (Original post by thesmallman)
Really confused about something guys!!Uno when u use contingency tables for chi squared u do (row-1)(column-1) to get degrees of freedom- if you then pool/combine a row (frequencies<5) do u take 1 away from the value of v?I.e. (3-1)(2-1)-1?Thanks!!
Nope, then you work out v with the new number of rows and columns.
16. A fair die is rolled 35 times. Find the approximate probability that the total of the 35 scores is less than 100.

For this how do you get the variance and mean

I know how to do the CLT part, just stuck on this - is it discrete uniform? how would I calculate the mean and var
17. (Original post by Zacken)
Nope, then you work out v with the new number of rows and columns.
Oh so if one of the 'squares' of the table have frequencies<5, the entire column is merged with the one on the left?
18. (Original post by thesmallman)
Oh so if one of the 'squares' of the table have frequencies<5, the entire column is merged with the one on the left?
Yes.
19. (Original post by L'Evil Wolf)
A fair die is rolled 35 times. Find the approximate probability that the total of the 35 scores is less than 100.

For this how do you get the variance and mean

I know how to do the CLT part, just stuck on this - is it discrete uniform? how would I calculate the mean and var
Yeh dicrete uniform.
Mean is 3.5 by symmetry. Calculate E(X^2) by the sum of scores squred tkmes 1/6. Then varx=E(x^2)-((ex))^2

Posted from TSR Mobile
20. (Original post by physicsmaths)
Yeh dicrete uniform.
Mean is 3.5 by symmetry. Calculate E(X^2) by the sum of scores squred tkmes 1/6. Then varx=E(x^2)-((ex))^2

Posted from TSR Mobile

ah ofc!

Thank you.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 29, 2016
Today on TSR

### Should I drop out of uni

...to become a pro gamer?

### University open days

• University of Buckingham
Fri, 14 Dec '18
• University of Lincoln
Mini Open Day at the Brayford Campus Undergraduate
Wed, 19 Dec '18
• University of East Anglia
Fri, 4 Jan '19
Poll
Useful resources

Can you help? Study help unanswered threadsStudy Help rules and posting guidelinesLaTex guide for writing equations on TSR

## Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE