Review

Exhibit 8-1 In order to estimate the average time spent on the computer terminals per student at a local university, data were collected from a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.2 hours. Refer to Exhibit 8-1. With a 0.95 probability, the margin of error is approximately Selected Answer: Incorrecta. 1.64 Answers: a. 1.64 Correctb. 0.26 c. 1.96 d. 0.21

B

Exhibit 8-1 In order to estimate the average time spent on the computer terminals per student at a local university, data were collected from a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.2 hours. Refer to Exhibit 8-1. If the sample mean is 9 hours, then the 95% confidence interval is approximately Selected Answer: Incorrectb. 7.04 to 110.96 hours Answers: a. 7.80 to 10.20 hours b. 7.04 to 110.96 hours c. 7.36 to 10.64 hours Correctd. 8.74 to 9.26 hours

D

A random sample of 144 observations has a mean of 20, a median of 21, and a mode of 22. The population standard deviation is known to equal 4.8. The 95.44% confidence interval for the population mean is Answers: a. 19.2 to 20.8 b. 15.2 to 24.8 c. 19.216 to 20.784 d. 21.2 to 22.8

a

Exhibit 8-3 A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph. Refer to Exhibit 8-3. The value to use for the standard error of the mean is Selected Answer: Correcta. 1.5 Answers: Correcta. 1.5 b. 13.5 c. 2.26 d. 9

a

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%. Refer to Exhibit 9-6. At a .05 level of significance, it can be concluded that the proportion of the population in favor of candidate A is Selected Answer: Incorrectd. not significantly greater than 75% Answers: Correcta. significantly greater than 75% b. significantly greater than 80% c. not significantly greater than 80% d. not significantly greater than 75%

a

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%. Refer to Exhibit 9-6. The test statistic is Selected Answer: Incorrectd. 2.00 Answers: Correcta. 1.25 b. 0.80 c. 0.05 d. 2.00

a

The z value for a 97.8% confidence interval estimation is Selected Answer: Incorrectb. 2.00 Answers: Correcta. 2.29 b. 2.00 c. 1.96 d. 2.02

a

Which of the following hypotheses applies to a situation where action must be taken both when H 0 cannot be rejected and when H 0 can be rejected? Selected Answer: Incorrectc. Answers: Correcta. b. c. d.

a

n = 16 H0: μ ≥ 80 = 75.607 Ha: μ < 80 σ = 8.246 Assume population is normally distributed. Refer to Exhibit 9-5. If the test is done at a 2% level of significance, the null hypothesis should Selected Answer: Correcta. not be rejected Answers: Correcta. not be rejected b. be rejected c. Not enough information is given to answer this question. d. None of the other answers are correct.

a

n = 49 H0: μ = 50 = 54.8 Ha: μ ≠ 50 σ = 28 Refer to Exhibit 9-3. If the test is done at a 5% level of significance, the null hypothesis should Selected Answer: Correcta. not be rejected Answers: Correcta. not be rejected b. be rejected c. Not enough information given to answer this question. d. None of the other answers are correct.

a

n = 49 H0: μ = 50 = 54.8 Ha: μ ≠ 50 σ = 28 Refer to Exhibit 9-3. The test statistic equals Selected Answer: Incorrectd. 0.3849 Answers: Correcta. 1.2 b. 0.1714 c. -1.2 d. 0.3849

a

Exhibit 8-3 A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph. Refer to Exhibit 8-3. If we are interested in determining an interval estimate for μ at 86.9% confidence, the z value to use is Selected Answer: Incorrectd. 1.96 Answers: a. 1.31 Correctb. 1.51 c. 2.00 d. 1.96

b

Exhibit 9-1 n = 36 H0: μ ≤ 20 = 24.6 Ha: μ > 20 σ = 12 Refer to Exhibit 9-1. If the test is done at a .05 level of significance, the null hypothesis should Selected Answer: Correctb. be rejected Answers: a. not be rejected Correctb. be rejected c. Not enough information is given to answer this question. d. None of the other answers are correct.

b

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. Refer to Exhibit 9-2. At a .05 level of significance, it can be concluded that the mean of the population is Selected Answer: Incorrecta. significantly less than 3 Answers: a. significantly less than 3 Correctb. significantly greater than 3 c. not significantly greater than 3 d. significantly greater then 3.18

b

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%. Refer to Exhibit 9-6. The p-value is Selected Answer: Incorrectd. 0.05 Answers: a. 0.2112 Correctb. 0.0156 c. 0.025 d. 0.05

b

For a two-tailed hypothesis test about μ, we can use any of the following approaches except Selected Answer: Correctb. compare the level of significance to the confidence coefficient Answers: a. compare the confidence interval estimate of μ to the hypothesized value of μ Correctb. compare the level of significance to the confidence coefficient c. compare the value of the test statistic to the critical value d. compare the p-value to the value of α

b

In hypothesis testing, the hypothesis tentatively assumed to be true is Selected Answer: Correctb. the null hypothesis Answers: a. the alternative hypothesis Correctb. the null hypothesis c. either the null or the alternative d. None of the other answers are correct.

b

In the past, 75% of the tourists who visited Chattanooga went to see Rock City. The management of Rock City recently undertook an extensive promotional campaign. They are interested in determining whether the promotional campaign actually increased the proportion of tourists visiting Rock City. The correct set of hypotheses is Selected Answer: Incorrecta. H 0: p ≥ 0.75 H a: p < 0.75 Answers: a. H 0: p ≥ 0.75 H a: p < 0.75 Correctb. H 0: p ≤ 0.75 H a: p > 0.75 c. H 0: p < 0.75 H a: p ≥ 0.75 d. H 0: p > 0.75 H a: p ≤ 0.75

b

More evidence against H 0 is indicated by Selected Answer: Incorrectc. lower levels of significance Answers: a. smaller critical values Correctb. smaller p-values c. lower levels of significance d. lower probabilities of a Type II error

b

The t distribution should be used whenever Selected Answer: Correctb. the sample standard deviation is used to estimate the population standard deviation Answers: a. the sample size is less than 30 Correctb. the sample standard deviation is used to estimate the population standard deviation c. the population is not normally distributed d. None of the other answers are correct.

b

n = 16 H0: μ ≥ 80 = 75.607 Ha: μ < 80 σ = 8.246 Assume population is normally distributed. Refer to Exhibit 9-5. The p-value is equal to Selected Answer: Incorrecta. 0.0332 Answers: a. 0.0332 Correctb. 0.0166 c. 0.9834 d. -0.0166

b

n = 36 H0: μ ≤ 20 = 24.6 Ha: μ > 20 σ = 12 Refer to Exhibit 9-1. The test statistic equals Selected Answer: Incorrecta. -0.38 Answers: a. -0.38 Correctb. 2.3 c. -2.3 d. 0.38

b

Exhibit 8-1 In order to estimate the average time spent on the computer terminals per student at a local university, data were collected from a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.2 hours. Refer to Exhibit 8-1. The standard error of the mean is Selected Answer: Incorrectd. 7.5 Answers: a. 0.014 b. 0.160 Correctc. 0.133 d. 7.5

c

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. Refer to Exhibit 9-2. The p-value is Selected Answer: Correctc. 0.0228 Answers: a. 0.025 b. 0.05 Correctc. 0.0228 d. 0.0456

c

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. Refer to Exhibit 9-2. The test statistic is Selected Answer: Correctc. 2.00 Answers: a. 1.64 b. 1.96 Correctc. 2.00 d. 0.056

c

In the hypothesis testing procedure, α is Selected Answer: Correctc. the level of significance Answers: a. 1 − level of significance b. the critical value Correctc. the level of significance d. the confidence level

c

The probability of making a Type I error is denoted by Selected Answer: Correctc. α Answers: a. β b. 1 − β Correctc. α d. 1 − α

c

The t value with a 95% confidence and 24 degrees of freedom is Selected Answer: Incorrectd. 2.492 Answers: a. 1.711 b. 2.069 Correctc. 2.064 d. 2.492

c

Two approaches to drawing a conclusion in a hypothesis test are Selected Answer: Incorrectd. null and alternative Answers: a. Type I and Type II b. one-tailed and two-tailed Correctc. p-value and critical value d. null and alternative

c

Which of the following does not need to be known in order to compute the p-value? Selected Answer: Correctc. the level of significance Answers: a. knowledge of whether the test is one-tailed or two-tailed b. the value of the test statistic Correctc. the level of significance d. All of these are needed.

c

n = 16 H0: μ ≥ 80 = 75.607 Ha: μ < 80 σ = 8.246 Assume population is normally distributed. Refer to Exhibit 9-5. The test statistic equals Selected Answer: Incorrectb. 2.131 Answers: a. 0.53 b. 2.131 Correctc. -2.131 d. -0.53

c

A 95% confidence interval for a population mean is determined to be 100 to 120. If the confidence coefficient is reduced to 0.90, the interval for μ Answers: a. becomes 0.1 b. becomes wider c. does not change d. becomes narrower

d

A random sample of 25 employees of a local company has been measured. A 95% confidence interval estimate for the mean systolic blood pressure for all company employees is 123 to 139. Which of the following statements is valid? Selected Answer: Incorrecta. 95% of the sample of employees has a systolic blood pressure between 123 and 139. Answers: a. 95% of the sample of employees has a systolic blood pressure between 123 and 139. b. If the sampling procedure were repeated many times, 95% of the sample means would be between 123 and 139. c. 95% of the population of employees has a systolic blood pressure between 123 and 139. Correctd. If the sampling procedure were repeated many times, 95% of the resulting confidence intervals would contain the population mean systolic blood pressure.

d

A sample of 26 elements from a normally distributed population is selected. The sample mean is 10 with a standard deviation of 4. The 95% confidence interval for μ is Selected Answer: Correctd. 8.384 to 11.616 Answers: a. 6.000 to 14.000 b. 9.846 to 10.154 c. 8.462 to 11.538 Correctd. 8.384 to 11.616

d

Exhibit 8-3 A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph. Refer to Exhibit 8-3. The 86.9% confidence interval for μ is Selected Answer: Incorrecta. 59.131 to 60.869 Answers: a. 59.131 to 60.869 b. 46.500 to 73.500 c. 50 to 70 Correctd. 57.735 to 62.265

d

For a two-tailed hypothesis test about a population mean, the null hypothesis can be rejected if the confidence interval​ Selected Answer: Incorrecta. ​ is symmetric Answers: a. ​ is symmetric b. ​ is non-symmetric c. ​ includes μ 0 Correctd. ​ does not include μ0

d

For a two-tailed hypothesis test with a test statistic value of z = 2.05, the p-value i​ Selected Answer: Correctd. ​.0404 Answers: a. ​.0101 b. ​.0202 c. ​.4899 Correctd. ​.0404

d

If a hypothesis test has a Type I error probability of .05, that means​ Selected Answer: Correctd. ​ if the null hypothesis is true, it will be rejected 5% of the time Answers: a. ​ if the null hypothesis is true, it will not be rejected 5% of the time b. ​ if the null hypothesis is false, it will not be rejected 5% of the time c. ​ if the null hypothesis is false, it will be rejected 5% of the time Correctd. ​ if the null hypothesis is true, it will be rejected 5% of the time

d

n = 36 H0: μ ≤ 20 = 24.6 Ha: μ > 20 σ = 12 Refer to Exhibit 9-1. The p-value is Selected Answer: Incorrectb. 0.5107 Answers: a. 2.1 b. 0.5107 c. 0.0214 Correctd. 0.0107

d

n = 49 H0: μ = 50 = 54.8 Ha: μ ≠ 50 σ = 28 Refer to Exhibit 9-3. The p-value is equal to Selected Answer: Incorrecta. 0.1151 Answers: a. 0.1151 b. 0.3849 c. 0.2698 Correctd. 0.2302

d