Question 179649: 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. (b) Why is the normality assumption not a problem, despite the very small value of p?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! 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. (b) Why is the normality assumption not a problem, despite the very small value of p?
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p-hat = 1143/86991 = 0.01316...
E = 1.96*sqrt[0.01316*0.98684../86991] = 0.0003863
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95% CI: 0.01316-0.0003863 < p < 0.01316+0.0003863
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n is so large np > 5 and nq > 5.
Cheers,
Stan H.
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