A study of 420,076 cell phone users found that 133 of them developed cancer of t
ID: 2933164 • Letter: A
Question
A study of 420,076 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 0.0441% 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 ot nervous system.
________ % < p < ________ % (Round to three decimal places as needed.)
b. Do cell phones users appear to have a rate of cancer of the brain or nervous system that is different from the rate of such cancer among those not using cell phones? Why or why not?
Yes, because 0.0441% is included in the confidence interval.
Yes, because 0.0441% is NOT included in the confidence interval
No, because 0.0441% is NOT included in the confidence interval.
No, because 0.0441% is included in the confidence level.
Explanation / Answer
here sample proportion p=133/420076=0.0003
std error =(p(!-p)/n)1/2 =0.000027
for 90% CI ; z =1.6449
hence 90% confidence interval of the percentage =sample proportion -/+ z*std error =0.027% <p <0.036%
Yes, because 0.0441% is NOT included in the confidence interval
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