Proportional confidence interval formula:
CI90 = p ± (1.645)[√(pq/n)]
...where p = x/n, q = 1 - p, and n = sample size.
Note: ± 1.645 represents 90% confidence interval.
For p in your problem: 135/420048
For q: 1 - p = q
n = 420048
I let you take it from here to calculate the interval. (Note: convert all fractions to decimals.)
You should be able to answer the second part of this problem once you have calculated the interval.
A study of 420,048 cell phone users found that 135 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 0.0333% 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
?% <p< ?%
round to four decimal places as needed
b. Do cell phone 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?
a. Yes because 0.0333% is not included in the confidence interval
b. No because 0.0333% is not included in the confidence interval
c. Yes because 0.0333% is included in the confidence interval
d. No because 0.0333% is included in the confidence interval
1 answer
1 answer