Question

Please help!
See attachment.

Answer 1

@jim_thompson5910 can u help?

Answer 2

to compute the test statistic, use this formula

t = (xbar - mu)/(s/sqrt(n))

Answer 3

i got that its the answer i'm not understanding. like in the example. Where did the -1.04 come from?

Answer 4

that's what you get when you type the previous step into a calculator and evaluate

Answer 5

they jumped a few steps, but hopefully you can use your calculator to get the same thing

Answer 6

Well can u explain the steps there skipping cause that's i'm lost.

Answer 7

ok one sec

Answer 8

when i solve it i get 0.0496 so were how'd they get -1.04?

Answer 9

oh you might be using different numbers

in the example, they're using different values for xbar and s

so that's probably why you're getting a different answer

Answer 10

but let me check

Answer 11

no I'm getting -0.81607512375926, one sec while I type it out

Answer 12

Test Statistic


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


\[\large t = \frac{37.4 - 40}{\frac{14.6}{\sqrt{21}}}\]


\[\large t = \frac{37.4 - 40}{\frac{14.6}{4.58257569495583}}\]


\[\large t = \frac{37.4 - 40}{3.1859811974455}\]


\[\large t = \frac{-2.6}{3.1859811974455}\]


\[\large t = -0.81607512375926\]

Answer 13

i'm working on the example.

Answer 14

ok hold on

Answer 15

From the example...


Test Statistic


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


\[\large t = \frac{47.5 - 50}{\frac{11}{\sqrt{21}}}\]


\[\large t = \frac{47.5 - 50}{\frac{11}{4.58257569495584}}\]


\[\large t = \frac{47.5 - 50}{2.40039679259592}\]


\[\large t = \frac{-2.5}{2.40039679259592}\]


\[\large t = -1.04149447612633\]


\[\large t = -1.04\]

Answer 16

ok i'm gunna try to solve it like that to see if i get the same.

Answer 17

well dang. lol i got -1.04. i guess i'm supposed to solve it step by step not all at once.

Answer 18

you can jump to the end if you type it into your calculator properly

Answer 19

you would type in

(47.5 - 50)/(11/sqrt(21))

to get -1.04149447612633

Answer 20

i was putting it into mathway.

Answer 21

oh you're probably better off using a TI calculator or something like that

Answer 22

ok so the answer for (37.4-40)/(14.6/sqrt(21))=-0.82?

Answer 23

that's correct

Answer 24

it's saying i'm wrong.

Answer 25

oh you need to go to 3 decimal places (not 2)

Answer 26

so t = -0.816

Answer 27

i did that -0.816

Answer 28

hmm

Answer 29

oh n = 22, not n = 21, so t = -0.835

Answer 30

oh lol ok it's right now

Answer 31

now part b)

Answer 32

i think it's 1.721

Answer 33

one sec

Answer 34

n = 22 still right?

Answer 35

i thought u do n-1 so it be 22-1=21?

Answer 36

ok thought so, yeah df = n-1

Answer 37

and I'm getting 1.721 as well

Answer 38

but it's negative since we have a left tail test

Answer 39

well it says it's wrong. :(

Answer 40

yeah it should be -1.721 since it's a left tail test

Answer 41

YAY that's right! lol

Answer 42

lol great

Answer 43

you got what

Answer 44

i think it's B

Answer 45

yep, you got it

Answer 46

left tail test ----> rejection region (shown in blue) is in left tail to left of critical value

Answer 47

what was the test statistic

what is the critical value

Answer 48

-0.835 & -1.721?

Answer 49

so is the test statistic

a) to the left of the critical value

or

b) to the right of the critical value

Answer 50

a)?

Answer 51

-0.835 is to the left of -1.721?

ie you're saying

-0.835 is less than -1.721?

Answer 52

UGH idk to the right then?

Answer 53

think of a number line, the number -1.721 is further away from 0 than -0.835 is

so that's why -0.835 is to the right of -1.721

Answer 54

since the test statistic does NOT lie in the critical region (aka the rejection region) you fail to reject the null hypothesis

Answer 55

you only reject the null hypothesis if the test statistic lies in the blue critical region or rejection region

in this case, it does not, so you fail to reject the null

Answer 56

ok so ether B or C right?

Answer 57

@jim_thompson5910

Answer 58

do you reject the null hypothesis (based off what I just said)

Answer 59

no?

Answer 60

UGH i have know idea!

Answer 61

you sound unsure, you're correct though

Answer 62

basically the value -0.835 is NOT in the blue rejection region

so that's why you don't reject the null

Answer 63

so i IS ether B or C?

Answer 64

it's C because you don't reject the null

Answer 65

and you don't reject the null since it's not in the rejection region

Answer 66

great! lol got time to help with another question?

Answer 67

sure

Answer 68

one more

Answer 69

THANK YOU!!

Answer 70

np

Answer 71

one min

Answer 72

kk

Answer 73

hmm I'm on the fence as to whether to use n = 148 or n = 500

because it makes a huge difference in the answer

Answer 74

and is there an example given? if so, then I'm curious as to if it uses scientific notation

Answer 75

Hows this?

Answer 76

yeah it's kinda lame because the answer is so small that it's practically 0

Answer 77

I'm getting 1.1756 * 10^(-21) which is basically 0 since it's so small

so that's why I think you just enter 0.0000

Answer 78

HAHAHA that was the answer! now can u explain exactly what u did to get that so i know next time.

Answer 79

well I first found the test statistic, which is -9.938

then I found the area to the left of that test statistic using df = 499

the answer I got was 1.1756 * 10^(-21)

Answer 80

ok that makes a little sense.

Answer 81

I used wolfram alpha's tcdf function to get the area

Answer 82

lol i never understand how to use wolfram alpha.

Answer 83

thank you for the help. I seem to need it a lot. lol odds are i'll be back on tomorrow.

Answer 84

you're welcome