Question

When 2426 voters were polled, 25% said they were voting yes on an initiative measure.Find the margin of error and an interval that is likely to contain the true population

proportion.

±4.9%; between 20.1% and 29.9%

±20%; between 5% and 45%

±49.3%; between 0.0% and 74.3%

±2%; between 23% and 27%

Answer 1

@agent0smith

Answer 2

About the same as last time, show your work.

Answer 3

im not sure on this one?

Answer 4

How is it different to the last? Hint: it's not.

Answer 5

i know i just don't get this one

Answer 6

Do the same steps as the last one. I don't know what there is to not get?

Answer 7

If you could do that last one, you can do this one.

Answer 8

i just don't know what numbers to put in

Answer 9

How were you able to do all this correctly:

phat = 81/368 = 0.2201086957 ≈ 0.22

q = 1 - 0.2201086957 = 0.7798913043 = 0.78

P(0.22 - 1.96*sqrt(0.22*0.78/368) < π < 0.22 + 1.96*sqrt(0.22*0.78/368) ) = 0.95

P(0.22 - 0.04 < π < 0.22 + 0.04) = 0.95

P(0.18 < π < 0.26) = 0.95

sample proportion = 0.18
margin of error = 0.04

But be lost on this question?

Answer 10

This problem doesn't state what the confidence level is. Does your teacher want you to assume 95% confidence?

Answer 11

yeah i think so

Answer 12

Is that because you got that last one from here???
https://answers.yahoo.com/question/index?qid=20120623162446AAqJJMX

Answer 13

You'll use this formula to find the margin of error (ME)

\[\Large ME = 1.96*\sqrt{\frac{p*(1-p)}{n}}\]

where we have 95% confidence, p is the sample proportion, n is the sample size

Answer 14

no i had done this question for a previous assignment and just found my work for it

Answer 15

And it just happened to be copied and pasted from yahoo answers...

Answer 16

p=When 2426 voters were polled, n=25%

Answer 17

@jim_thompson5910

Answer 18

p = 0.25 because 25% voted 'yes'

Answer 19

n = 2426 is the sample size

Answer 20

o ok

Answer 21

sqrt.1875/2426= Me?

Answer 22

@jim_thompson5910

Answer 23

how are you getting 1875?

Answer 24

did you mean

0.25*0.75 = 0.1875

??

Answer 25

yes sorry

Answer 26

use a calculator and tell me what `sqrt(0.1875/2426)` is equal to

Answer 27

0.00879134326

Answer 28

@jim_thompson5910

Answer 29

now multiply that by 1.96 to get what?

Answer 30

0.01723103279

Answer 31

multiply that by 100 to convert to a percentage

Answer 32

1.72310327997

Answer 33

so roughly 1.7% which rounds to 2%

Answer 34

right so answer d

Answer 35

the confidence interval is then based on the margin of error

25% - 2% = 23%
25% + 2% = 27%

the margin of error is from 23% to 27%

most often in studies, you'll see "margin of error plus or minus 2%" or something like that

Answer 36

`right so answer d`
yes