Need help with 13c.
For an alternative conclusion it would mean we would reject Ho, so our z value would be less than -1.645?
Not sure how you work out the sum of x^2 though.
Thanks
hmm that is a bit ****, it doesn't allow me to upload the photo? Anyone know how to fix that problem?
I think this should work: http://i64.tinypic.com/2ppc9ap.jpg
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Super199
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- 07-11-2015 13:58
Last edited by Super199; 07-11-2015 at 16:06. -
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- 07-11-2015 14:36
(Original post by Super199)
Need help with 13c.
For an alternative conclusion it would mean we would reject Ho, so our z value would be less than -1.645?
Not sure how you work out the sum of x^2 though.
Thanks
hmm that is a bit ****, it doesn't allow me to upload the photo? Anyone know how to fix that problem?
What message do you get? -
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- 07-11-2015 15:24
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- 07-11-2015 15:26
(Original post by Super199)
The attachments thing and it comes up with a server error. -
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- 07-11-2015 15:42
(Original post by SeanFM)
Maybe try insert image if possible? -
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- 07-11-2015 15:48
(Original post by Super199)
Doesn't work either. :/
Hm.. it may be worth typing it out?
Or finding the same question online somewhere if possible.Last edited by Kevin De Bruyne; 07-11-2015 at 15:50. -
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- 07-11-2015 15:52
(Original post by Super199)
Need help with 13c.
For an alternative conclusion it would mean we would reject Ho, so our z value would be less than -1.645?
Not sure how you work out the sum of x^2 though.
Thanks
hmm that is a bit ****, it doesn't allow me to upload the photo? Anyone know how to fix that problem? -
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- 07-11-2015 16:04
(Original post by SeanFM)
Hm.. it may be worth typing it out?
Or finding the same question online somewhere if possible.
btw where was that photo taken? -
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- 07-11-2015 16:36
I think that what you said about the z value is correct - and we can assume that the sum of x (and so the sample mean are correct), so the thing that we're in interested in is theta/n, which depends on the sum of x^2... -
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- 08-11-2015 00:20
(Original post by SeanFM)
University of Bath campus, by the lake
I think that what you said about the z value is correct - and we can assume that the sum of x (and so the sample mean are correct), so the thing that we're in interested in is theta/n, which depends on the sum of x^2... -
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- 08-11-2015 01:48
(Original post by Super199)
theta/n?)
The only unknown is sigma (the standard deviation) which depends on the variance, which depends on the sum of x^2.. so can you see how to find the 'correct' value of sigma? -
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- 08-11-2015 19:50
(Original post by SeanFM)
Sorry, I got sigma and theta mixed up (I'm doing stats work involving theta, sorry!)
The only unknown is sigma (the standard deviation) which depends on the variance, which depends on the sum of x^2.. so can you see how to find the 'correct' value of sigma?
What I have done is put the standard deviation = sum of x^2/n - mean^2
Thought the standard deviation would be the square root of my sample variance and then tried rearranging for sum of x^2 -
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- 08-11-2015 19:52
(Original post by Super199)
Not really.
What I have done is put the standard deviation = sum of x^2/n - mean^2
Thought the standard deviation would be the square root of my sample variance and then tried rearranging for sum of x^2 -
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- 08-11-2015 19:59
(Original post by SeanFM)
Yes, that's correct... now the only thing you're missing is the standard deviation.
I used the equation and got 82.7?Last edited by Super199; 08-11-2015 at 20:01. -
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- 08-11-2015 20:01
(Original post by Super199)
Yeah but what is the standard deviation? -
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- 08-11-2015 20:08
(Original post by SeanFM)
It's to do with the value for which the hypothesis is rejected. -
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- 08-11-2015 20:12
(Original post by Super199)
Nah idek anymore i give up haha -
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- 08-11-2015 20:23
(Original post by SeanFM)
From what I understand, the sample mean is fixed, the mean that you're testing (30) is fixed, and the z value that you need to get from the test to get a different conclusion (which you've already identified) so you need to find the value of the standard deviation that satisfies that equation, and then you can use the formula you've just defined (for the sum of x^2).
The answer is 106610.5
You may need to give me a full solution. I would try and post my working but attachments dont seem to work.
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- 08-11-2015 20:55
(Original post by Super199)
For the rejection of Ho. It would have to be -1.646>-1.645?
The answer is 106610.5
You may need to give me a full solution. I would try and post my working but attachments dont seem to work.
I seem to be getting 106665 which is out by a bit, so perhaps the method is wrong.
Last edited by Kevin De Bruyne; 08-11-2015 at 20:57. -
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- 08-11-2015 21:15
(Original post by SeanFM)
I seem to be getting 106665 which is out by a bit, so perhaps the method is wrong.
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