Deck 28: Application of Confidence Interval Estimation in Auditing

Question 1

TABLE 8-16
The president of a university is concerned that the percentage of students who have cheated on an exam is higher than the 1% acceptable level.A confidential random sample of 1,000 students from a population of 7,000 revealed that 6 of them said that they had cheated on an exam during the last semester.
True or False: Referring to Table 8-16,the president can be 90% confident that no more than 1% of the students at the university had cheated on an exam during the last semester.

Answer 1

True

Question 2

TABLE 8-15
The president of a university is concerned that illicit drug use on campus is higher than the 5% targeted level.A random sample of 250 students from a population of 2,000 revealed that 7 of them had used illicit drugs during the last 12 months.
Referring to Table 8-15,what is the upper bound of the 90% one-sided confidence interval for the proportion of students who had used illicit drugs during the last 12 months?

Answer 2

0.0405

Question 3

TABLE 8-15
The president of a university is concerned that illicit drug use on campus is higher than the 5% targeted level.A random sample of 250 students from a population of 2,000 revealed that 7 of them had used illicit drugs during the last 12 months.
Referring to Table 8-15,what is the critical value for the 90% one-sided confidence interval for the proportion of students who had used illicit drugs during the last 12 months?

Answer 3

1.2816 (using PHStat)or 1.28 (using Table E.2)

Question 4

TABLE 8-14
The superintendent of a unified school district of a small town wants to make sure that no more than 5% of the students skip more than 10 days of school in a year.A random sample of 145 students from a population of 800 showed that 12 students skipped more than 10 days of school last year.
Referring to Table 8-14,what is the upper bound of the 95% one-sided confidence interval for the proportion of students who skipped more than 10 days of school last year?

Question 5

TABLE 8-15
The president of a university is concerned that illicit drug use on campus is higher than the 5% targeted level.A random sample of 250 students from a population of 2,000 revealed that 7 of them had used illicit drugs during the last 12 months.
True or False: Referring to Table 8-15,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 drugs during the last 12 months.

Question 6

TABLE 8-16
The president of a university is concerned that the percentage of students who have cheated on an exam is higher than the 1% acceptable level.A confidential random sample of 1,000 students from a population of 7,000 revealed that 6 of them said that they had cheated on an exam during the last semester.
True or False: Referring to Table 8-16,using the 90% one-sided confidence interval,the president can be 95% confident that no more than 1% of the students at the university had cheated on an exam during the last semester.

Question 7

TABLE 8-15
The president of a university is concerned that illicit drug use on campus is higher than the 5% targeted level.A random sample of 250 students from a population of 2,000 revealed that 7 of them had used illicit drugs during the last 12 months.
True or False: Referring to Table 8-15,using the 90% one-sided confidence interval,the president can be 95% confident that no more than 5% of the students at the university had used illicit drugs during the last 12 months.

Question 8

TABLE 8-15
The president of a university is concerned that illicit drug use on campus is higher than the 5% targeted level.A random sample of 250 students from a population of 2,000 revealed that 7 of them had used illicit drugs during the last 12 months.
True or False: Referring to Table 8-15,the president can be 90% confident that no more than 5% of the students at the university had used illicit drugs during the last 12 months.

Question 9

TABLE 8-14
The superintendent of a unified school district of a small town wants to make sure that no more than 5% of the students skip more than 10 days of school in a year.A random sample of 145 students from a population of 800 showed that 12 students skipped more than 10 days of school last year.
Referring to Table 8-14,what is the critical value for the 95% one-sided confidence interval for the proportion of students who skipped more than 10 days of school last year?

Question 10

TABLE 8-16
The president of a university is concerned that the percentage of students who have cheated on an exam is higher than the 1% acceptable level.A confidential random sample of 1,000 students from a population of 7,000 revealed that 6 of them said that they had cheated on an exam during the last semester.
Referring to Table 8-16,what is the critical value for the 90% one-sided confidence interval for the proportion of students who had cheated on an exam during the last 12 months?

Question 11

TABLE 8-16
The president of a university is concerned that the percentage of students who have cheated on an exam is higher than the 1% acceptable level.A confidential random sample of 1,000 students from a population of 7,000 revealed that 6 of them said that they had cheated on an exam during the last semester.
True or False: Referring to Table 8-16,using the 90% one-sided confidence interval,the superintendent can be 85% confident that no more than 1% of the students at the university had cheated on an exam during the last semester.

Question 12

TABLE 8-14
The superintendent of a unified school district of a small town wants to make sure that no more than 5% of the students skip more than 10 days of school in a year.A random sample of 145 students from a population of 800 showed that 12 students skipped more than 10 days of school last year.
True or False: Referring to Table 8-14,the superintendent can conclude with 95% level of confidence that no more than 5% of the students in the unified school district skipped more than 10 days of school last year.

Question 13

TABLE 8-16
The president of a university is concerned that the percentage of students who have cheated on an exam is higher than the 1% acceptable level.A confidential random sample of 1,000 students from a population of 7,000 revealed that 6 of them said that they had cheated on an exam during the last semester.
Referring to Table 8-16,what is the upper bound of the 90% one-sided confidence interval for the proportion of students who had cheated on an exam during the last 12 months?