Question 277743
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.
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sample proportion = 1143/86991 = 0.013
standard error = E = 1.96sqrt(0.013*0.987/86991) = 0.000753
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(a) Construct a 95 percent confidence interval for the population proportion of positive drug tests.
95% CI: 0.013-0.000753 < p < 0.013+0.000753
95% CI: 0.01222 < p < 0.013753
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(b) Why is the normality assumption not a problem, despite the very small value of p?
I'll leave that to you.
Cheers,
Stan H.