SOLUTION: A study of 420,065 cell phone users found that 136 of them developed cancer of the brain or nervous system. Prior to this study of cell phone​ use, the rate of such cancer was fo

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Question 1182743: A study of 420,065 cell phone users found that 136 of them developed cancer of the brain or nervous system. Prior to this study of cell phone​ use, the rate of such cancer was found to be 0.0316​% for those not using cell phones.
Use the sample data to construct a 95​% confidence interval estimate of the percentage of cell phone users who develop cancer of the brain or nervous system.
__% < p < __​%
(Round to three decimal places as​ needed.)
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
The 95% half-interval is z(0.975)*sqrt(p*(1-p)/n)
=1.96*sqrt(0.000316*0.999684/420065)
=0.0000274; add that and subtract it from 0.000323, p hat.
so the interval is (0.000296, 0.000350)
or (0.030%, 0.0350%)