TABLE 8-10
The president of a university is concerned that illicit drug use on campus is higher than the 5% acceptable level. A random sample of 250 students from a population of 2,000 revealed that 7 of them had used illicit drug during the last 12 months.
-Referring to Table 8-10, using the 90% one-sided confidence interval, the president can be 85% confident that no more than 5% of the students at the university had used illicit drug during the last 12 months.

Question

Quizplus · Accepted Answer

The confidence interval is 0.025 to 0.115, which means that the president can be 90% confident that the true proportion of students who have used illicit drugs in the last 12 months is between 2.5% and 11.5%. Since the upper bound of the confidence interval is less than 5%, the president can be 85% confident that no more than 5% of the students at the university have used illicit drugs in the last 12 months.

TABLE 8-10 The President of a University Is Concerned That Illicit Drug