applied statistics in Business and Economic?
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?
Here we can only calculate the proportion with one show; the theory sustain it is required a more numbers of shows.
One show give a perfect interval of confidence (100 percent), which following the problem you ask it is better than 95%.
then a) 1.31%
b) normality assumption is not a problem because the probability of plus than 5% could be cero; so we can find the figure of bell around the value 1.31%.