x Turn on thread page Beta
 You are Here: Home >< Maths

# Statistics S1B 17/05/2013 Thread watch

1. (Original post by Problematique)
ah that makes sense thanks. So a is the y intercept as in when x=0?
Yes and b is the gradient
2. (Original post by Son234)
You forgot to put for the final 3rd Mark for the b value that

There is a negative relationship/correlation as the b value is -0.076

The question is 3 marks

This was posted from The Student Room's iPhone/iPad App
Mark scheme says:
b: each 1(%) rise in moisture content B2
reduces calorific value
by 0.076 MWh/tonne
So saying that gets you two marks.
3. (Original post by Gotzz)
Mark scheme says:
b: each 1(%) rise in moisture content B2
reduces calorific value
by 0.076 MWh/tonne
So saying that gets you two marks.
Ahh I thought it was B1

This was posted from The Student Room's iPhone/iPad App
4. Tomorrow I've done loads of past papers but probability always seems to trip me up. I hate probability. Everything else is fine though. Just want to get it over with
5. What does it mean when something is mutually exclusive and independent?

This was posted from The Student Room's iPhone/iPad App
6. (Original post by Son234)
3ci) you just calculate the mean and variance of the 12 values as normal

Mean= 2
Variance = 2.33

3cii)

You compare the mean and variance of your 12 values to the mean and variance of B(16,0.20) and B(16,0.125)

B(16,0.20)
Different mean similar variance

Np= 3.2 npq= 2.56

B(16, 0.125)

Np=2 npq= 1.75

Same mean different variance

Thus both models unsuitable

This was posted from The Student Room's iPhone/iPad App
Thanks man, but how did you work out the variance?
7. Can somebody explain Question 4aiii and 4bi and 4bii to me on Jan 2010 paper.

For 4 aiii i did: (0.10x0.45x0.45)+(0.55x0.45x0.9) +(0.55x0.10x0.55) = 0.273

for 4bi i did: 0.9 x 0.7 = 0.63
bii i did : 0.1x0.3 = 0.03

I know the mark scheme is clear on how to do it. Its just why they did it like that.

Also, when explaining PMCC, when is it a Very strong positive/strong positive/positive/weak/very weak/negligible correlation and when is it Very strong negative/strong negative/negative/weak negative/very weak negative/negligible correlation

Can somebody also explain conditional probability in relation to how to work out Union, intersect and given probabilities.

Final problems for me is recognising when to use the formulae np(1-p) and np in the test.
8. hey anybody, need urgent help with question 6di) on jan 2009 paper
here is the paper: http://stourport.neogic.com/docs/rev...W-QP-JAN09.pdf
here is the ms - http://www.gosford-hill.oxon.sch.uk/...W-MS-JAN09.pdf
can anyone explain to me?
Thanks
9. (Original post by med123)
hey anybody, need urgent help with question 6di) on jan 2009 paper
here is the paper: http://stourport.neogic.com/docs/rev...W-QP-JAN09.pdf
here is the ms - http://www.gosford-hill.oxon.sch.uk/...W-MS-JAN09.pdf
can anyone explain to me?
Thanks
A residual can be found by:

Residual = Observed value - Predicted value

So you need to work out the residuals for H,I and J as they are males.

Observing the table you know that y values for H I and J are 41,46,51 for observed values

For predicted values you just have to insert the x values for H I and J into your regression line equation.

Remember a - residual indicates that your observed values are below your regression line and a + value indicates your observed values are above your regression line. The smaller the difference is between 0 and the value of the residual, the closer it is to the regression line equation.

Once you done that work out the 3 residuals and then work out the mean of them by doing:

(R1+R2+R3)/3 where R1,R2,R3 is each residual.
10. (Original post by neymarFanboy)
Thanks man, but how did you work out the variance?
Use your calculator plot a table of just x with the 12 values

And it works out the mean and variance for you

This was posted from The Student Room's iPhone/iPad App
11. (Original post by Son234)
Probability of either A or B happening but not both is p(A and B') + p(A' and B)

Probability of either A or B happening is the union

So P(A) + P(B) - P(A n B)

This was posted from The Student Room's iPhone/iPad App
thanks!!

everything seems to be okay, apart from probability which is really, for me, down to luck and the difficulty of the question :P
also, anyone know when you have to use the stuff about 'all values lie within 2/3/4 standard deviations of the mean' blah blah, like i get what it means but how are you supposed to know when you are supposed to write that kind of thing? what does it relate to?! thanks
12. (Original post by georgiaaaxo)
thanks!!

everything seems to be okay, apart from probability which is really, for me, down to luck and the difficulty of the question :P
also, anyone know when you have to use the stuff about 'all values like within 2/3/4 standard deviations of the mean' blah blah, like i get what it means but how are you supposed to know when you are supposed to write that kind of thing? what does it relate to?! thanks
You use it to check if something can be normally distributed or a claim where they say a bag contains 1kg

And then you use your mean minus 1 or 2 or 3 x standard deviation

Not 4 btw

This was posted from The Student Room's iPhone/iPad App
13. (Original post by Son234)
Use your calculator plot a table of just x with the 12 values

And it works out the mean and variance for you

This was posted from The Student Room's iPhone/iPad App
The calculator gives you the mean and standard deviation only.

To get the variance , you then need to times the SD by itself to give the variance .
14. (Original post by Son234)
You use it to check if something can be normally distributed or a claim where they say a bag contains 1kg

And then you use your mean minus 1 or 2 or 3 x standard deviation

Not 4 btw

This was posted from The Student Room's iPhone/iPad App
ohhh okay! and also to estimate the standard deviation? i think that was in the last question in jan 13. thanks!
15. (Original post by Tha Realest)
The calculator gives you the mean and standard deviation only.

To get the variance , you then need to times the SD by itself to give the variance .
My graphical calculator gives the variance but yeah make sure you square the standard deviation as mentioned ^^

This was posted from The Student Room's iPhone/iPad App
16. (Original post by Son234)
My graphical calculator gives the variance but yeah make sure you square the standard deviation as mentioned ^^

This was posted from The Student Room's iPhone/iPad App
Sorry lol ... I have a Casio fx-83GT PLUS , I was assuming he wasn't using a graphical calculator.

Anyway how you feeling for S1 tomorrow ??
17. (Original post by seajamiet)
A residual can be found by:

Residual = Observed value - Predicted value

So you need to work out the residuals for H,I and J as they are males.

Observing the table you know that y values for H I and J are 41,46,51 for observed values

For predicted values you just have to insert the x values for H I and J into your regression line equation.

Remember a - residual indicates that your observed values are below your regression line and a + value indicates your observed values are above your regression line. The smaller the difference is between 0 and the value of the residual, the closer it is to the regression line equation.

thanks so much

Once you done that work out the 3 residuals and then work out the mean of them by doing:

(R1+R2+R3)/3 where R1,R2,R3 is each residual.

thanks so much
18. Can someone please explain question 7A and 7B from the AQA January 2013 S1 paper thanks.

Cheers
19. (Original post by Tha Realest)
Sorry lol ... I have a Casio fx-83GT PLUS , I was assuming he wasn't using a graphical calculator.

Anyway how you feeling for S1 tomorrow ??
Feeling like a boss....

Just kidding going to fail

I think it's going to be really hard with a lot of tricky questions

Where AQA try and catch you out

This was posted from The Student Room's iPhone/iPad App
20. (Original post by Son234)
Feeling like a boss....

Just kidding going to fail

I think it's going to be really hard with a lot of tricky questions

Where AQA try and catch you out

This was posted from The Student Room's iPhone/iPad App

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: May 27, 2013
Today on TSR

### Happy St Patrick's day!

How are you celebrating?

### Stay at sixth form or go to college?

Discussions on TSR

• Latest
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
Discussions on TSR

• Latest

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