Posted by **Jon** on Sunday, November 24, 2013 at 1:45pm.

142 out of 507 people were right. Calculate a 95% confidence interval for the proportion of the entire population that could be right. I did some of the work and got .72...don't know what to do with this? Please help.

- Statistics -
**Kuai**, Sunday, November 24, 2013 at 2:00pm
p = 142/ 507 = 0.28

SD = sqrt(p(1-p)/n)

0.28-+ 0.039

(.241, .319)

- Statistics -
**Jon**, Sunday, November 24, 2013 at 2:27pm
so I could say that with 95% confidence, between 24.1% and 31.9% of the entire population could be right?

- Statistics -
**Jon**, Sunday, November 24, 2013 at 2:56pm
you know I am getting .0199 SD =srt(.28(1-.28)/506 = .0119? Please check for me again?

- Statistics -
**kuai**, Sunday, November 24, 2013 at 3:13pm
YES. IF YOUR PROFESSOR SAID THAT YOUR ANSWER SHOULD BE IN PERCENT.

P = 142/507 = 0.28

SD = SQRT( .28*.72/507)

SQRT(0.2016/507) = 0.0199

Z = 1.96

0.28-+1.96*0.0199

0.28-+ 0.039

( 0.241, 0.319)

- Statistics -
**Jon**, Sunday, November 24, 2013 at 3:23pm
I get it now...I was missing a step too! Thanks Much!

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