Statistics S1B 17/05/2013 Thread

ah that makes sense thanks. So a is the y intercept as in when x=0?

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



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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.

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


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hey anybody, need urgent help with question 6di) on jan 2009 paper
here is the paper: http://stourport.neogic.com/docs/revision/AQA-MS-SS1B-W-QP-JAN09.pdf
here is the ms - http://www.gosford-hill.oxon.sch.uk/past-exam-papers/alevel-maths/alevel-maths/Statistics/Stats%201B/Stats%201B%20Mark%20Schemes/AQA-MS-SS1B-W-MS-JAN09.pdf
can anyone explain to me?
Thanks

Thanks man, but how did you work out the variance?

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)




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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

Use your calculator plot a table of just x with the 12 values

And it works out the mean and variance for you


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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


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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 ^^


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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.

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


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