Question 185152This question is from textbook Applied Statistics
: 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? (Data are from Flying 120, no. 11 [November 1993], p. 31.)
This question is from textbook Applied Statistics
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.
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sample proportion = 1143/86991 = 0.013
E = 1.96 * [0.13*0.87 / 86991] = 0.000386
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95% CI: 0.013 - 0.000386 < p < 0.013 + 0.000386
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(b) Why is the normality assumption not a problem, despite the very small value of p?
n is very large
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Cheers,
Stan H.
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