<PRE><B>Question 135350</B>
In 1992, the FAA conducted 86,991 pre-employment drug tests on job applicants who were to be engaged in safety and security-related jobs, and found that 1,143 were positive. 
(a) Construct a 95 percent confidence interval for the population proportion of positive drug tests. 
p-hat = 1143/86991 = 0.013139...
E = 1.96*sqrt[(0.013139)*(0.98686)/86991] = 0.002393
CI is (0.013139-0.002393,0.013139+0.00239)
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(b) Why is the normality assumption not a problem, despite the very small value of p? The random sample was very large.
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Cheers,
StanH.</PRE>