ATAR Notes: Forum
VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Mathematical Methods CAS => Topic started by: matt123 on November 07, 2010, 06:20:31 pm
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Hey guys
http://www.vcaa.vic.edu.au/vcaa/vce/studies/mathematics/cas/pastexams/2009/2009mmCAS2-w.pdf
Q3d
how do u work out the Z value?
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?
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we are asking the same in this thread posted an hour ago
http://vcenotes.com/forum/index.php/topic,33059.0.html
also!!! they used 99.5% but WHY!
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we are asking the same in this thread posted an hour ago
http://vcenotes.com/forum/index.php/topic,33059.0.html
also!!! they used 99.5% but WHY!
Problem is
no one explained how to actually find the Z value
i got no clue.
someone please help
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0.5% need to be under the range, and 0.5% need to be over.
Therefore, to get a z-value, you just go invNorm(0.005,0,1) Remember that 0.5% is 0.005.
then to get s.d. you just rearrange the z score formula
z=(x-mean)/s.d.
s.d.=(x-mean)/z
s.d.=(65.6-67)/-2.57583
= 54mm
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Well u know that 99% of balls from 65.6<X<68.4. So that means there are two areas outside this interval: (-∞, 65.6] and [68.4,∞). So the are in each of these is (1-.99)/2=0.05. Then you know the area from (-∞, 65.6] is 0.005. So the z value that corresponds to this is found by using invNorm(Area=0.005,µ=0, sd=1)
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0.5% need to be under the range, and 0.5% need to be over.
Therefore, to get a z-value, you just go invNorm(0.005,0,1) Remember that 0.5% is 0.005.
then to get s.d. you just rearrange the z score formula
z=(x-mean)s.d.
s.d.=(x-mean)/z
s.d.=(65.6-67)/-2.57583
= 54mm
Buddy
it wont work for me
i go to INV norm
type
0.005 prob
1
0
and i get "invalid"
lol
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http://vcenotes.com/forum/index.php/topic,33059.0.html
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Just go to normal distrubution and then write in lower and uper terminals, and mean. then write x for S.D.
then make that expression = 0.99 and solve for x.
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Just go to normal distrubution and then write in lower and uper terminals, and mean. then write x for STD.
then make that expression = 0.99 and solve for x.
yeah i did and it worked thanks
but where did u get 0.995 from? isnt it 0,997?
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btw
did it again'
and it worked thanks
but where did u get 0.995 from? isnt it 0,997
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.997 is for 3 standard deviations either side of the mean.
We want .99, so the whole .997 mumbo-jumbo is irrelevant :)
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.997 is for 3 standard deviations either side of the mean.
We want .99, so the whole .997 mumbo-jumbo is irrelevant :)
so then how did u get .995?
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.997 is for 3 standard deviations either side of the mean.
We want .99, so the whole .997 mumbo-jumbo is irrelevant :)
so then how did u get .995?
its because on either side of 0.99 is 0.005
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LOL refer to the other thread we were talking in. :)