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S2 Jan 2007 Q5 Edexcel

Can someone please explain to me part C onward? The mark scheme is no use and I don't understand how the variable X applies to this situation
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Zacken
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Original post by Jordan97
Can someone please explain to me part C onward? The mark scheme is no use and I don't understand how the variable X applies to this situation


Link to the paper, please?
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Jordan97
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Original post by Zacken
Link to the paper, please?


Sorry, question 5 on this paper: http://qualifications.pearson.com/content/dam/pdf/A%20Level/Mathematics/2013/Exam%20materials/S2_Jan_2007_Paper.pdf
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Zacken
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Original post by Jordan97


Well, the question says that "the length in cm of the piece of wire with the ring on it is represented by the random variable X".

So since X is uniformly distributed on (0, 150), the mean of X is...?
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Jordan97
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Original post by Zacken
Well, the question says that "the length in cm of the piece of wire with the ring on it is represented by the random variable X".

So since X is uniformly distributed on (0, 150), the mean of X is...?


That's what I don't understand though, why is X uniformly distributed on (0, 150) when the values of a and b are -2 and 6
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Zacken
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Original post by Jordan97
That's what I don't understand though, why is X uniformly distributed on (0, 150) when the values of a and b are -2 and 6


No, this part of the question has nothing to do with the previous part of the question. This is a new X. Defined in the paragraph above (c).
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Original post by Zacken
No, this part of the question has nothing to do with the previous part of the question. This is a new X. Defined in the paragraph above (c).


Ah okay, I think that is quite misleading though, why didn't they use Y or some other letter or explicitly say a different variable??
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Zacken
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Original post by Jordan97
Ah okay, I think that is quite misleading though, why didn't they use Y or some other letter or explicitly say a different variable??


Well, to be fair, they did re-define it.
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Jordan97
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Original post by Zacken
Well, to be fair, they did re-define it.


True, thank you for your help though!
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Zacken
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Original post by Jordan97
True, thank you for your help though!


No worries, glad it's sorted!

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