iPad 10:51 PM * 61%- MyMathLab Homework STAT 130 - Spring 2018-MWF 10AM Kria Alw

Question

iPad 10:51 PM * 61%- MyMathLab Homework STAT 130 - Spring 2018-MWF 10AM Kria Alward 4/4/18 10:51 PM Homework: HW #8-Chapter 7-Cls for Proportions Save Score: 0.33 of 1 pt 9 of 14 (12 complete) ? HW Score: 64.76%, 9.07 of 14 pts 7 2.27 Question Help A study of 420,082 cell phone users found that 133 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 0.0317% for those not using cell phones. Complete parts (a) and (b). a. Use the sample data to construct a 90% confidence interval estimate of the percentage of cell phone users who develop cancer of the brain or nervous system. (Round to three decimal places as needed.) Enter your answer in the edit fields and then click Check Answer part remaining Clear All Check Answer

Explanation / Answer

Solution : Given that n = 420,082
p^ = 0.0317% = 0.000317, q^ = 1-p^ = 1 - 0.000317 = 0.999683
90% confidence interval for z = 1.645
E = z * sqrt(pq/n)
= 1.645 * sqrt((0.000317*0.999683)/420082)
= 0.00004518139
90% confidence interval estimate of the percentage of cellphone users
=> p^-E < p < p^+E
=> 0.000317 - 0.00004518139 < p < 0.000317 + 0.00004518139
=> 0.027% < p < 0.036%

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