Chapter 9 Blackboard Practice Questions and Assignment

Read the t statistic from the table of t distributions and circle the correct answer. A two-tailed test, a sample of 20 at a .20 level of significance, t= A. 1.328 B. 2.539 C. 1.325 D. 2.528

A. 1.328

A type 2 error is committed when A. a true alternative hypothesis is mistakenly rejected B. a true null hypothesis is mistakenly rejected C. the sample size has been too small D. not enough information has been available

A. a true alternative hypothesis is mistakenly rejected

The error of rejecting a true null hypothesis is A. a type 1 error B. a type 2 error C. an be either a or b, depending on the situation D. committed when not enough information is available

A. a type 1 error

A two-tailed test is a A. hypothesis test in which rejection region is in both tails of the sampling distribution B. hypothesis test in which rejection region is in one tail of the sampling distribution C. hypothesis test in which rejection region is only in the lower tail of the sampling distribution D. hypothesis test in which rejection region is only in the upper tail of the sampling distribution

A. hypothesis test in which rejection region is in both tails of the sampling distribution

Exhibit 9-4: A random sample of 16 students from the student body of a large university had an average age of 25 years. We want to determine if the average age of all the students at the university is significantly different from 24. Assume the distribution of the population of ages is normal with a standard deviation of 2 years. At a 0.05 level of significance, it can be concluded that the mean age is A. not significantly different from 24 B. significantly different from 24 C. significantly less than 24 D. significantly less than 25

A. not significantly different from 24

A p-value is the A. probability, when the null hypothesis is true, of obtaining a sample result that is at least as unlikely as what is observed B. value of the test statistic C. probability of a type 2 error D. probability corresponding to the critical value(s) in a hypothesis test

A. probability, when the null hypothesis is true, of obtaining a sample result that is at least as unlikely as what is observed

Exhibit 9-2: The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took the customers in the sample to check out was 3.1 minutes. The population standard deviation is known to be 0.5 minutes. We want to test to determine whether or not the mean waiting time of all customers is significantly more than 3 minutes. At a 0.05 level of significance, it can be concluded that the mean of the population is A. significantly greater than 3 B. not significantly greater than 3 C. significantly less than 3 D. significantly greater than 3.18

A. significantly greater than 3

Exhibit 9-6: A random sample of 100 people was taken. Eighty of the people in the sample favored Candidate A. We are interested in determining whether or not the proportion of the population in favor of Candidate A is significantly more than 75%. At a 0.05 level of significance, it can be concluded that the proportion of the population in favor of Candidate A is A. significantly greater than 75% B. not significantly greater than 75% C. significantly greater than 80% D. not significantly greater than 80%

A. significantly greater than 75%

For a sample size of 30, changing from using the standard normal distribution to using the t distribution in a hypothesis test, A. will result in the rejection region being smaller B. will result in the rejection region being larger C. would have no effect on the rejection region D. not enough information is given to answer this question

A. will result in the rejection region being smaller

Read the z statistics from the normal distribution table and circle the correct answer. A two-tailed test at a 0.0694 level of significance; z= A. -1.96 and 1.96 B. -1.48 and 1.48 C. -1.09 and 1.09 D. -0.86 and 0.86

B. -1.48 and 1.48

Read the z statistic from the normal distribution table and circle the correct answer. A one-tailed test (lower tail) at a 0.063 level of significance; z= A. -1.86 B. -1.53 C. -1.96 D. -1.645

B. -1.53

Exhibit 9-4: A random sample of 16 students from the student body of a large university had an average age of 25 years. We want to determine if the average age of all the students at the university is significantly different from 24. Assume the distribution of the population of ages is normal with a standard deviation of 2 years. The test statistic is A. 1.96 B. 2.00 C. 1.645 D. 0.05

B. 2.00

A type 1 error is committed when A. a true alternative hypothesis is not accepted B. a true null hypothesis is rejected C. the critical value is greater than the value of the test statistic D. sample data contradict the null hypothesis

B. a true null hypothesis is rejected

As a general guideline, the research hypothesis should be stated as the A. null hypothesis B. alternative hypothesis C. tentative assumption D. hypothesis the researcher wants to disprove

B. alternative hypothesis

For a one-tailed test (upper tail) with a sample size of 900, the null hypothesis will be rejected at the 0.05 level of significance if the test statistic is A. less than or equal to -1.645 B. greater than or equal to 1.645 C. less than 1.645 D. less than -1.96

B. greater than or equal to 1.645

A one-tailed test is a A. hypothesis test in which rejection region is in both tails of the sampling distribution B. hypothesis test in which rejection region is in one tail of the sampling distribution C. hypothesis test in which rejection region is only in the lower tail of the sampling distribution D. hypothesis test in which rejection region is only in the upper tail of the sampling distribution

B. hypothesis test in which rejection region is in one tail of the sampling distribution

A two-tailed test is performed at a 5% level of significance. The p-value is determined to be 0.09. The null hypothesis A. must be rejected B. should not be rejected C. may or may not be rejected, depending on the sample size D. has been designed incorrectly

B. should not be rejected

In hypothesis testing, the alternative hypothesis is A. the hypothesis tentatively assumed true in the hypothesis testing procedure B. the hypothesis concluded to be true if the null hypothesis is rejected C. the maximum probability of a type 1 error D. all of the answers are correct

B. the hypothesis concluded to be true if the null hypothesis is rejected

Read the t statistic from the table of t distributions and circle the correct answer. A one-tailed test (lower tail), a sample size of 10 at a .10 level of significance, t= A. 1.383 B. -1.372 C. -1.383 D. -2.821

C. -1.383

Exhibit 9-6: A random sample of 100 people was taken. Eighty of the people in the sample favored Candidate A. We are interested in determining whether or not the proportion of the population in favor of Candidate A is significantly more than 75%. The test statistic is A. 0.80 B. 0.05 C. 1.25 D. 2.00

C. 1.25

Exhibit 9-2: The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took the customers in the sample to check out was 3.1 minutes. The population standard deviation is known to be 0.5 minutes. We want to test to determine whether or not the mean waiting time of all customers is significantly more than 3 minutes. The test statistic is A. 1.96 B. 1.64 C. 2.00 D. 0.056

C. 2.00

If the cost of a type 1 error is high, a smaller value should be chosen for the A. critical value B. confidence coefficient C. level of significance D. test statistic

C. level of significance

Exhibit 9-6: A random sample of 100 people was taken. Eighty of the people in the sample favored Candidate A. We are interested in determining whether or not the proportion of the population in favor of Candidate A is significantly more than 75%. The p-value is A. 0.2112 B. 0.05 C. 0.025 D. 0.0156

D. 0.0156

Exhibit 9-2: The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took the customers in the sample to check out was 3.1 minutes. The population standard deviation is known to be 0.5 minutes. We want to test to determine whether or not the mean waiting time of all customers is significantly more than 3 minutes. The p-value is A. 0.025 B. 0.0456 C. 0.05 D. 0.0228

D. 0.0228

Read the z statistic from the normal distribution table and circle the correct answer. A one-tailed test (upper tail) at a 0.123 level of significance; z= A. 1.54 B. 1.96 C. 1.645 D. 1.16

D. 1.16

Read the t statistic from the table of t distributions and circle the correct answer. A one-tailed (upper tail), a sample size of 18 at a .05 level of significance, t= A. 2.12 B. 1.734 C. -1.740 D. 1.740

D. 1.740

For a two-tailed hypothesis test about m, we can use any of the following approaches except A. compare the confidence interval estimate of m to the hypothesized value of m B. compare the p-value to the value of a C. compare the value of the test statistic to the critical value D. compare the level of significance to the confidence coefficient

D. compare the level of significance to the confidence coefficient

For a two-tailed hypothesis test about a population mean, the null hypothesis can be rejected if the confidence interval A. is symmetric B. is non-symmetric C. includes m0 D. does not include m0

D. does not include m0

If a hypothesis test has a Type 1 error probability of 0.05, that means A. if the null hypothesis is false, it will not be rejected 5% of the time B. if the null hypothesis is false, it will be rejected 5% of the time C. if the null hypothesis is true, it will not be rejected 5% of the time D. if the null hypothesis is true, it will be rejected 5% of the time

D. if the null hypothesis is true, it will be rejected 5% of the time

the level of significance can be any A. negative value B. value C. value larger than 0.1 D. none of the answers is correct

D. none of the answers is correct

If a hypothesis test leads to the rejection of the null hypothesis, a A. type 2 error must have been committed B. type 2 error may have been committed C. type 1 error must have been committed D. type 1 error may have been committed

D. type 1 error may have been committed