Question

Help with stat please! I need to make sure i;m on the right track.
http://jdanforth.weebly.com/uploads/1/2/3/7/12370684/7.2_quiz.pdf

Answer 1

This is a quiz, so I'll only be able to offer hints. What was your question?

Answer 2

It's not an actual quiz, its just the worksheets she gives us and I happened to find a pdf for it. On number 1, how would you format the answers (.22 and .0338) into sentence format? Also on #2, how would you know if its normally distributed other than the 10% rule or is that it?

Answer 3

ok one sec

Answer 4

you're referring to 1a) right? or something else?

Answer 5

yes

Answer 6

you have the correct answers

I'd just fit them into a sentence like this "the mean is ____ and the standard deviation is ___"

I guess you can be creative and say something like "the center is located at ____ and the sampling distribution has a standard deviation of ____ which determines how spread out the sampling distribution is"

I'm not sure, but something like that

Answer 7

Ah okay! Sometimes our teacher prefers to put it in context of the problem but I wasnt really sure how to do it that way.

Answer 8

well I guess you could say

"the average percentage is centered around 22% and it's spread out with a standard deviation of 3.38%"

Answer 9

usually when it comes to describing percentages, and how they are spread out, you use a margin of error. But we need a confidence level for that.

Answer 10

Ah okay. And for the 1D, how would you find that? I know the formula for SD and the mean but not sure how to apply it here for these requirements

Answer 11

let me think about 1D, one sec

Answer 12

thank you

Answer 13

ok I found this

http://courses.wcupa.edu/rbove/Berenson/10th%20ed%20CD-ROM%20topics/section7_3.pdf

do you see the formula in the second blue box? hopefully that formula looks familiar

Answer 14

I have actually ever seen that formula before! But I'll tr to figure it out.

Answer 15

well that formula allows you to calculate the standard error if you are dealing with a finite population (usually relatively small)

Answer 16

standard error = std dev of sampling distribution

Answer 17

actually, sorry, you're using the formula for box 3

Answer 18

not box 2

Answer 19

can I ask what method they show in the textbook?

Answer 20

I cant find where they did it in the textbook...

Answer 21

ok on that pdf I sent you, do you see where it says at the top of page 1

"In these cases, particularly when the sample size n is not small in comparison with the population size N (i.e., more than 5% of the population is sampled) so that n/N > 0.05, a finite population correction factor (fpc) is used to define both the standard error of the mean and the standard error of the proportion"

Answer 22

so I'm thinking that IF the sample size n is too big, then you have to use that finite population correction factor (fpc)

If it is not too big, then you can get away without using the fpc

Answer 23

n/N > 0.05

n/600 > 0.05

600*(n/600) > 0.05*600

n > 30

So if n > 30, then you have to use the fpc. If n <= 30, then you can get away without using the fpc

Answer 24

I'm not seeing how it applies but also I'm not sure if I should use that given its nowhere at all in my text book :x We can skip to the last one for now, which I'm also having trouble with (2b). I keep getting 0 on the calculator using normcdf

Answer 25

well since I got n > 30 leads to using the fpc, I'm thinking 30 is the max on the sample size

Answer 26

that makes a bit of sense. I'll try to sort it out in my brain in a minute (Its past 12 here and I'm exhausted)

Answer 27

how are you typing things in for 2b?

Answer 28

I just got that one! :)

Answer 29

ok great

Answer 30

yep. thank you so much by the way cx

Answer 31

you're welcome