SOLUTION: Out of 600 people sampled, 342 had kids. Based on this, construct a 90% confidence interval for the true population proportion of people with kids. Give your answers as decimals

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Question 1198839: Out of 600 people sampled, 342 had kids. Based on this, construct a 90% confidence interval for the true population proportion of people with kids.
Give your answers as decimals, to three places

Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
the proportion of people that have kids is 342 / 600 = .57
the proportion of people that don't have kids is .43
p = .57
q = 1 -.57 = .43
n = total number of people = 600
standard deviation is sqrt(p * q / n) = .57 * .43 / 600) = .0202113829.
z-score is used.

formula for z-score is:
z = (x - m) / s
z is the z-score
x is the raw score
m is the mean
s is the standard deviation

the critical z-score at 90% two tailed confidence interval is equal to plus or minus 1.644853626.

low side z-score formula becomes -1.644853626 = (x - .57) / .0202113829 = .5367552335.

high side z-score formula becomes 1.644853626 = (x - .57) / .0202113829 = .6032447665.

the 90% confidence interval is from .537 to .603 rounded to 3 decimal places.