Question 455403: 2.) 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.)
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! 2.) 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.
---
phat = 1143/86991 = 0.01314
(a) Construct a 95 percent confidence interval for the population proportion of positive drug tests.
---
ME = 1.96*sqrt[0.01314*0.98696/86991] = 0.000757
-----------------------
95% CI: 0.01314-0.000757 < p < 0.01314+0.000757
95% CI: 0.012383 < p < 0.013897
==================
(b) Why is the normality assumption not a problem, despite the very small value of p?
Ample sample size.
=====================
cheers,
Stan H.
|
|
|
