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Mathematics 7 Online
OpenStudy (anonymous):

See attachment for question

OpenStudy (anonymous):

OpenStudy (anonymous):

@amistre64 can u help with this?

OpenStudy (amistre64):

prolly .... i find the way they present the long tiny text to be, disorientating ...

OpenStudy (anonymous):

lol yah me to

OpenStudy (amistre64):

\[\Large Z=\frac{u_1-u_2}{\sqrt{\frac{s^2_1}{n_1}+\frac{s^2_2}{n_2}}}\] or it may be a T score thing, sounds familiar

OpenStudy (anonymous):

yah that looks familiar

OpenStudy (amistre64):

or i spose: a more confidence interval setup would be: \[[u_1-u_2]\pm Z_{.95}\sqrt{that~stuff}\]

OpenStudy (anonymous):

no i think it's the other way cause that looks familiar to me

OpenStudy (amistre64):

the other was is just a zscore presentation. confidence intervals take on a slightly modified version of it

OpenStudy (amistre64):

\[[5.37-4.23]\pm(2.575)\sqrt{\frac{(2.33)^2+(1.96)^2}{40}}\]

OpenStudy (anonymous):

:( that looks familiar to!

OpenStudy (anonymous):

OMG

OpenStudy (anonymous):

now u r just confusing me :(

OpenStudy (amistre64):

do you recall confidence intervals?\[u\pm Z\sqrt{\frac{\sigma^2}{n}}\]

OpenStudy (anonymous):

yes

OpenStudy (amistre64):

its just a version of that is all, using the mean/variance properties of 2 samples

OpenStudy (amistre64):

1.96 for Z on a 95% CI ... i read it as ((% to start with

OpenStudy (amistre64):

if i did it right, lets try: .20 and 2.08 as the range

OpenStudy (anonymous):

ok one sec. i'm looking through my notes

OpenStudy (anonymous):

FOUND IT!!!

OpenStudy (amistre64):

i can never find anything in my notes ... prolly since i dont take notes

OpenStudy (anonymous):

lmao well i had what week it was from and the question # so i could find it again.

OpenStudy (amistre64):

that looks to use the t distribution values instead of the z distributions ... which of course will produce similar but different values

OpenStudy (anonymous):

yup

OpenStudy (amistre64):

if we know the population variance ... which is seldom.... we could use the Z stuff, it used to be taught that n>30 would allow you to substitute Z for T

OpenStudy (anonymous):

from what i got the problem will look like this \[(5.37-4.23)\pm2.023\times \sqrt{\frac{ 2.33^{2} }{ 40 }+\frac{ 1.96^{2} }{40}}\]

OpenStudy (anonymous):

The lower bound is 0.17 The upper bound is 2.11

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