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Edexcel S3 - Wednesday 25th May AM 2016

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For the two assumptions make at the end of Q5 do you think 'That both data sets are assumed to be independant' is valid ?
Thanks :smile:
Original post by Unravelling
Did anyone else use the poisson formula to find the mean? I.e. e^-lambda = 16.53/100, and solve for lambda? I got the mean to be 1.7999... which gave me the same expected values and overall test statistic.


I did that and got 1.799.

I also worked out the mean from the table ( Sum of fx / sum of f ) and got 1.8, so i used 1.8.

Either way, the value of lambda will give similar results
Original post by econam
For the two assumptions make at the end of Q5 do you think 'That both data sets are assumed to be independant' is valid ?
Thanks :smile:


Yup. I think it'll be: both populations are independent and s^2 = sigma^2 for both populations
Original post by AmarPatel98
I did that and got 1.799.

I also worked out the mean from the table ( Sum of fx / sum of f ) and got 1.8, so i used 1.8.

Either way, the value of lambda will give similar results


I would assume both methods are allowed?
Reply 1384
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adris
1
For the final question I got >43.xx
Will I still get marks ?
Original post by AmarPatel98
Yup. I think it'll be: both populations are independent and s^2 = sigma^2 for both populations

I hope so because they are the ones I put! I have heard other people mention central limit theorem - maybe there is range of answers?
Original post by adris
For the final question I got >43.xx
Will I still get marks ?


You might lose an answer mark, but I think that's it
Reply 1387
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NSSBB
Original post by JoshC98
I think it was 12.005 for the first one, and 0.405 for the last one, so if you rounded to 12.01 and 0.41 you ended up being 0.01 over, so last one had to be adjusted to 0.40.[/QUO


But I think rounding both of them would not make any differences to the answer. Must we just round either of them?!
Reply 1388
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adris
1
The hypothesis killed me D-:
Reply 1389
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adris
1
Btw everyone all hail king @arsey he is no longer with us. Edexcel have claimed him. There goes anyone chances of checking marks /-:
How did people do 4a??
Original post by Unravelling
I would assume both methods are allowed?


Perhaps, since some Ei values were given, whereas in past papers they usually just tell you to work out the mean in the first part of the question. Ultimately, we have to find lambda so i think it's likely they'll credit both methods.

Original post by econam
I hope so because they are the ones I put! I have heard other people mention central limit theorem - maybe there is range of answers?


I dont think 'CLT applies' is a valid assumption. Usually, we mention that by the CLT, we assume the two sample means are normally distributed - but this answer is for the question 'What is the relevance of the CLT?'
Is there any way you can look back through your calculator memory (fx-991es)
Reply 1393
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Original post by Fbiemad
Can someone else also confirm how many marks Q4 part (a) was?
I heard few different answers (about the amount of marks for this question) so I dont know which one it is.

Part (a) was about difference in E being greater than 2.
P(I e1-e2 I > 2)


What is your answer? Can you remember?
What is the edexcel policy for marking in the following case:

The question was about the assumptions in the hypothesis test in our paper today. I wrote:
'CLT applied so we assume the sample means are distributed normally.
Assume the populations are independent.
Assume s^2 = sigma^2'

I think the last two are correct, but having written these three, will i get all the marks?
Reply 1395
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NSSBB
Original post by Unravelling
I had no idea of any other way to do it :P When i asked other classmates, none of them did it our way and just calculated it from the tables (0 x its probability, 1 x its probability etc). which I didn't get since there were missing values we had to solve


But I think rounding both of them would not make any differences to the answer. Must we just round either of them?!
Reply 1396
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Original post by magixmike
How did people do 4a??


Is the one about eggs?
Reply 1397
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NSSBB
Original post by AmarPatel98
Perhaps, since some Ei values were given, whereas in past papers they usually just tell you to work out the mean in the first part of the question. Ultimately, we have to find lambda so i think it's likely they'll credit both methods.



I dont think 'CLT applies' is a valid assumption. Usually, we mention that by the CLT, we assume the two sample means are normally distributed - but this answer is for the question 'What is the relevance of the CLT?'


I think CLT is compulsory.
Reply 1398
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NSSBB
Original post by AmarPatel98
What is the edexcel policy for marking in the following case:

The question was about the assumptions in the hypothesis test in our paper today. I wrote:
'CLT applied so we assume the sample means are distributed normally.
Assume the populations are independent.
Assume s^2 = sigma^2'

I think the last two are correct, but having written these three, will i get all the marks?


I wrote like this 1. S squared= sigma squared the sample variance is equal to the population variance. 2. The central limit theorem enables us to assume both of the sample means are normal. Because we are not told that the populations are normal but the sample sizes are large enough.

Actually I think the first and the last one are correct. In terms of the past paper, every time there are this kind of questions
Original post by NSSBB
I wrote like this 1. S squared= sigma squared the sample variance is equal to the population variance. 2. The central limit theorem enables us to assume both of the sample means are normal. Because we are not told that the populations are normal but the sample sizes are large enough.

Actually I think the first and the last one are correct. In terms of the past paper, every time there are this kind of questions


The CLT point is valid for the question 'What is the relevance of the CLT' in past papers though. Perhaps it might be credited in this paper, but i have my doubts

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