PLZ HELP!!! See attachment.

- anonymous

PLZ HELP!!! See attachment.

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- schrodinger

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- anonymous

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- anonymous

@Luis_Rivera so i'll take that as you don't know how to do it?

- anonymous

@amistre64 can you help with this?

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## More answers

- amistre64

which part is giving you room to pause?

- anonymous

all of it

- amistre64

lets work on the test stat first, what do you recall about computing a tscore?

- amistre64

\[t=\frac{\bar x-\mu}{s}\sqrt n\]

- anonymous

oh ok i thought that was the formula but i wasn't sure.

- amistre64

#3 suggests that you recall something about hypt testing to begin with
if we are looking for < or > its in a tail; if we are looking for =, its in both tails

- anonymous

When you say #3 you mean question c)?

- amistre64

part d, or #4 (i thought they was numbered) would suggest that the red is inbetween 2 values ...

- anonymous

for b) i did \[\frac{ 102.0-105 }{ \frac{ 5.8 }{ \sqrt{35} } }\] =-0.09

- amistre64

your setup is correct, but your calculation is off

- anonymous

i put it into mathway and it came out as 0.0874. so that makes it 0.09 right?

- amistre64

102-105 = -3
-3/5.8 = -0.51724
-0.51724 * sqrt(35) = -3.060...

- anonymous

so the answer would be -3.06?

- amistre64

thats what my ti83 gives me, yes

- amistre64

the standard deviation is 5.8/sqrt(35); or about .98
we are 3 to the left of center, giving us a little over -3 sds away

- anonymous

i'm getting something different.
102.0-105=-3
-3/5.8=-0.5172413793
-0.5172413793/sqrt(35)=-0.08742975049=-0.09

- amistre64

your not spose to divide that by sqrt(35)

- amistre64

\[\frac{a}{p/q}=\frac{a}{p}*q\]

- amistre64

if anything, 5.8/sqrt(35) = .98
-3/.98 = -3.06

- anonymous

ok i see that now.

- amistre64

part c has me a little confused, my book is stating a path:
type of test? two tailed (since H0 not= H1 hyp)
tstat to the left of right? ours is left since its negative
therefore Pvalue = 2x the area to the left of the t score

- amistre64

its twice the area since its 2 tailed ... got it

- anonymous

so c) is B?

- amistre64

thats what i had originally considered, and thats what im going with :)

- anonymous

ok
Is a) B?

- amistre64

my gut says no. but quite frankly i never was good at that kind of question. I want to say it yes, but cant really say why

- anonymous

well whats you're gut say it is?

- amistre64

my gut likes d, but its lied to me before :)
on c, my book shows the pvalue area redshaded to the left, and says the pvalue is twice the area shaded ... which has me thinking that c is also just left shaded

- anonymous

then i will go with that. :)

- anonymous

now d)

- amistre64

how do you normally find the area? ti83 by chance?

- anonymous

no by hand or google

- amistre64

well, our zscore is -3.06 :) and we want the area to the left of it

- anonymous

so that would be...?

- amistre64

i thought you had indicated that you could find that area .... by hand or by google

- amistre64

http://www.danielsoper.com/statcalc3/calc.aspx?id=2

- anonymous

that's confusing.
1.25 means...?

- amistre64

1.25 is just a primer, our z score we found is -3.06
enter it into the box and hit calculate, it will give you the cumulative area up to z = -3.06

- anonymous

it gave me 0.00110668

- amistre64

im thinking that this is the lower bound, the area that is in the "red" we want to double that for an upper bound.

- anonymous

i'm thinking d) is A

- amistre64

...me too, but then again im only going off of what im reading in my stats book. if in reading it incorrectly, then i cant really guarentee the accuracy of my "guidance"

- amistre64

my ti83 gives a T-test, p-value of .004, which is not a range like the options .... nor is it really in the range of .001 to .002 ....

- amistre64

of course that next question has alot of 4s in it
.004 * 1000 = 4

- anonymous

ok that means...?

- amistre64

at the moment, that means im conflicted between what the book says, and what the overall problem set is telling us.
if p = .004, that would suggest that our range is between 002 and 005, but thats not the results i get from doing the process in the book. I simply dont have enough experience at this to know what, if anything, i am doing wrong :/

- anonymous

well whats your best guess?

- anonymous

i'd go with the book.

- amistre64

lol, the book doesnt jive with the next problem tho, so im thinking ive missed something.
ti83 and the test stat by hand each give us -3.06
this should be the zscore value as well, unless there is some z to t adjustment that im missing

- anonymous

lol well i'll take a guess cause this problem is giving me a headache. lol

- amistre64

give me about 10 minutes to review a youtube :)

- anonymous

lol ok

- amistre64

got it

- amistre64

we should not have used the "normal" distribution with a t-score

- amistre64

when i use the tCDF, with 1 degree of freedom:
tCDF(-9999,-3.06,35-1) = .00215
and doubled is .00430

- anonymous

?

- amistre64

in short, i assumed the t = z .... so our Pvalue is between .0021 and .0043

- amistre64

this will correspond to the next problem

- anonymous

so c) is C?

- amistre64

im going with C, yes :)

- anonymous

so to Interpret that it would be...?

- amistre64

well, to guide you to this, we just tested a mean of 102, and it has a Pvalue (probability value) of .4 % .... or .4 in every 100
how would you use this to determine (d) ?

- amistre64

if you expected to be paid: .004 cents for every hour you worked
how much would you make in 10 hours? in 100? in 1000?

- anonymous

.004*10?

- amistre64

yes, so .04 cents for 10 hours ...
and for 100?

- anonymous

0.4

- amistre64

good, 100 for .4 match an option? or do we need to go to 1000?

- anonymous

well 1000 is 4

- amistre64

so, its either B or C
notice that the name on our little paycheck is "102" since thats what this Pvalue is attributed to

- amistre64

we should expect that in 1000 hours, mister 102 will be paid 4

- anonymous

so it's C?

- amistre64

gut says C :)

- anonymous

good now e)

- amistre64

(e) has to do with something im more familar with, a confidence interval

- amistre64

the area to reject the is termed alpha, that a looking thing

- amistre64

the expected value of a = .01
our pvalue is at best: .004
we rejecct the null hypotheses if the pvalue is less then or equal to the "a" value

- anonymous

so it's yes?

- amistre64

correct

- anonymous

Great! got time to help with 1 more short question?

- amistre64

not really, i have to be heading home.

- anonymous

lol ok thx for the help!

- amistre64

good luck with this :)

- anonymous

THX!

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