In: Statistics and Probability
SOLUTION:
From given data,
A study of 420,026 cell phone users found that 138 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 0.0411% for those not using cell phones. The data are from the Journal of the National Cancer Institute.
Where,
x = 138
n = 420026
p = x/n = 138/420026 = 0.000328
q = 1-p = 1-0.000328 = 0.999672
a. 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.
95% confidence interval
Confidence interval is 95%
95% = 95/100 = 0.95
= 1 - Confidence interval = 1-0.95 = 0.05
/2 = 0.05 / 2
= 0.025
Z/2 = Z0.025 = 1.96
Margin of error = Z/2 * sqrt(p(1-p) / n)
Margin of error = 1.96 * sqrt(0.000328(1-0.000328) / 420026 ) = 0.0000547
95% C.I
Lower limit = p - Margin of error = 0.000328 - 0.0000547 = 0.00027 = 0.027 %
Upper limit = p + Margin of error = 0.000328 +0.0000547 = 0.00038 = 0.038 %