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#21
05-30-2004, 07:18 PM
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Tree Diagrams - Love 'em!!
  Can't share the same opinion as you about Pure maths though RichieW! I found the pure modules the hardest to relate to because it couldn't be applied to anything - it was just 'tricks with numbers'! Stats I hated cos it was all about probability, which I've never been able to do except, for some strange (if rather fortunate) reason, in the actual exam which had 3 of the 4 questions on it! Mechanics I could do when I thought about it but we had a rather boring teacher who only added colour to the lessons by throwing board-rubbers at us! 
__________________
www.gavin-buckley.com 
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#22
05-31-2004, 12:49 AM
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Quote:
b) A = the employee lives close to the company B = the employee is a manager P(A/B) = P(A AND B) / P(B) P(A AND B) = 6/125 P(B) = 20/125 So, P(A/B) = 6/20 = 30% If you don't want to use P(A/B) you can just say that the managers are 20 and only 6 of them live close, so 6/20 managers live close to the company. e) A = the employee is in production B = the employee is married P(A AND B) = 0.8*70 / 125 P(B) = (0.9*20 + 0.6*35 + 0.8*70) / 125 P(A/B) = 0.8*70 / (0.9*20 + 0.6*35 + 0.8*70) = ... If you have any problems with the above let me know
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#23
06-01-2004, 05:03 PM
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no spandex. no criminal records. no rehab. no pseudo-lesbian videos.  its just a really great record.
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#24
06-01-2004, 05:07 PM
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 good luck.
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#25
06-01-2004, 05:26 PM
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the dude abides 
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#26
06-02-2004, 12:14 PM
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i just failed my stats exam, will have to redo it in october
 the stuff panama has to do i have no problems with, but we're a bit further and its killing me
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#27
06-02-2004, 02:12 PM
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can anyone help me some more please?
ERM, anyone have a normal distribution table handy? dont worry if you cant cause like its not worth it really. will fail it anyway here it is: 1) the thickness of some sheets of wood follows a normal distribution with mean x and standard deviation y. 96% of the sheets will go through an 8mm gauge while only 1.7% will go through a 7mm gauge. find x and y. thanks to those who have a go!!! i get stuck after a while 
__________________
no spandex. no criminal records. no rehab. no pseudo-lesbian videos. its just a really great record.
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#28
06-02-2004, 03:50 PM
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#29
06-02-2004, 06:40 PM
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Quote:
I am not 100% sure ‘cause I haven’t worked with stats for some time now, but anyway, here is what I thought: P(V <= 8 10-3) = 0.96 P(V <= 7 10-3) = 0.017 Where V is our random variable (is that how you call it?) which represents the thickness of the sheets of wood. P(V <= 0.00  = P((V – x) / y <= (0.008 – x) / y) = F((0.008 – x) / y) = 0.96From the normal distribution table we have that F(1.75) = 0.96 So, (0.008 – x) / y = 1.75 P(V <= 0.007) = P((V – x) / y <= (0.007 – x) / y) = F((0.007 – x) / y) = 0.017 The normal distribution table doesn’t have values as low as 0.017 so we do the following trick: F((0.007 – x) / y) = 0.017 = 1 – 0.983 So, 1 - F((0.007 – x) / y) = 0.983 We know that F(-z) = 1 – F(z), hence F((x - 0.007) / y) = 0.983 From the normal distribution table we have that F(2.12) = 0.96 So, (x - 0.007) / y = 2.12 All you have to do now is to solve the 2 * 2 system and find x, y. Good luck!
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#30
06-06-2004, 03:58 PM
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thank you but i dont understand
. i get upto the part where you do the 'little trick' and then it gets fuzzy thank you for trying to help me out but i just dont get it or the right answers. thank you thank you but i just cant do it ill try to scan in my working but really its no use. thank you once again. you've been a really big help. thank you
__________________
no spandex. no criminal records. no rehab. no pseudo-lesbian videos. its just a really great record.
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