In: Statistics and Probability
A study of 420,042 cell phone users found that 130 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 0.0323% for those not using cell phones. Complete parts (a) and (b). 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.
a. __% < p < __%
a)
Level of Significance, α =
0.05
Number of Items of Interest, x =
130
Sample Size, n = 420042
Sample Proportion , p̂ = x/n =
0.0003
z -value = Zα/2 = 1.960 [excel
formula =NORMSINV(α/2)]
Standard Error , SE = √[p̂(1-p̂)/n] =
0.0000
margin of error , E = Z*SE = 1.960
* 0.0000 = 0.0001
95% Confidence Interval is
Interval Lower Limit = p̂ - E = 0.000
- 0.0001 = 0.00026
Interval Upper Limit = p̂ + E = 0.000
+ 0.0001 = 0.00036
95% confidence interval is ( 0.03% < p <
0.04% )