Salary information for a random sample of male and female employees of a large company is shown below.

MaleFemale

Sample Size / 64 / 36
Sample Mean Salary (in $1,000) / 44 / 41
Sample Variance / 128 / 72

The point estimate of the difference between the means of the two populations is

Select one:

A. -28

B. 3

C. 4

D. -4

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A carpet company advertises that it will deliver your carpet within 15 days of purchase. A sample of 49 past customers is taken. The average delivery time in the sample was 16.2 days with a standard deviation of 5.6 days. State the null and alternative hypotheses to test validity of claim being advertised.

Select one:

A. H0: μ 15
Ha: μ < 15

B. H0: μ 15
Ha: μ > 15

C. H0: μ = 15
Ha: μ 15

D. None of the above answers is correct

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"D" size batteries produced by MNM Corporation have had a life expectancy of 87 hours. Because of an improved production process, it is believed that there has been an increase in the life expectancy of its "D" size batteries. A sample of 36 batteries showed an average life of 88.5 hours. Assume from past information that it is known that the standard deviation of the population is 9 hours. If p-value is greater than significance level, what would be the conclusion?

Select one:

A. do not reject H0

B. reject H0

C. there is not enough information to answer this question

D. none of the above answers is correct

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Independent random samples taken on two university campuses revealed the following information concerning the average amount of money spent on textbooks during the fall semester.

University A / University B
Sample Size / 50 / 40
Average Purchase / $280 / $250
Standard Deviation / $20 / $23

At = .05, test to determine if, on the average, students at University A spend more on textbooks then the students at University B. What is the value of the test statistic?

Select one:

A. t test statistic = 4.512

B. t test statistic = 5.512

C. t test statistic = 6.512

D. t test statistic = -6.512

E. None of the above answers is correct

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The office of records at a university has stated that the proportion of incoming female students who major in business has increased. A sample of female students taken several years ago is compared with a sample of female students this year. Results are summarized below. Has the proportion increased significantly? Test at alpha = .10.

Sample Size / No. Majoring in Business
Previous Sample / 250 / 50
Present Sample / 300 / 69

If the test statistic for this problem is 0.85, what conclusion can be drawn?

Select one:

A. Reject null hypothesis, the proportion has not increased significantly

B. Reject null hypothesis, the proportion has increased significantly

C. Fail to reject null hypothesis, the proportion has not increased significantly

D. Fail to reject null hypothesis, the proportion has increased significantly

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Identify the null and alternative hypotheses for the following problem to detrmine whether the statement made by economists is valid. Economists have claimed that the marginal propensity to consume is at least 90 out of every dollar.

Select one:

A. H0: p 0.9
Ha: p > 0.9

B. H0: p 0.9
Ha: p < 0.9

C. H0: p = 0.9
Ha: p 0.9

D. None of the above answers is correct

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To compute an interval estimate for the difference between the means of two populations when samples are small, the t distribution can be used if it can be assumed that

Select one:

A. the populations are normally distributed

B. the variances are not equal

C. the population proportions are equal

D. the population means are equal

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If two independent large samples are taken from two populations, the sampling distribution of the difference between the two sample means

Select one:

A. can be approximated by a Poisson distribution

B. will have a variance of one

C. can be approximated by a normal distribution

D. will have a mean of one

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A new soft drink is being market tested. A sample of 400 individuals participated in the taste test and 80 indicated they like the taste. At 95% confidence, test to determine if at least 22% of the population will like the new soft drink.

Select one:

A. H0: μ 0.22
Ha: μ < 0.22

B. H0: μ 0.22
Ha: μ = 0.22

C. H0: μ = 0.22
Ha: μ 0.22

D. None of the above answers is correct

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For a two-tailed test, a sample of 20 at 80% confidence, t =

Select one:

A. 1.328

B. 2.539

C. 1.325

D. 2.528

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A pharmaceutical firm has requested that a medical doctor observe whether or not a new version of a drug has actually shortened the length of time it takes for a patient to feel the benefits of the medication. It can be assumed that the reaction time for the drug is normally distributed and that the standard deviations of the reaction times are equal for both versions of the drug. The doctor has administered the older drug and its new version to independent random samples of his patients.

Old
Version / New
Version
Sample Size / 15 / 10
Sample Mean / 80 minutes / 65 minutes
Sample Standard Deviation / 10 minutes / 14 minutes

What form should be used for the sampling distribution of the difference in means?

Select one:

A. Z distribution

B. a t distribution with 22 degrees of freedom

C. a t distribution with 23 degrees of freedom

D. None of the above answers is correct

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A carpet company advertises that it will deliver your carpet within 15 days of purchase. A sample of 49 past customers is taken. The average delivery time in the sample was 16.2 days with a standard deviation of 5.6 days. Test the null hypothesis at the 5% level of significance. What is the value of the test statistic?

Select one:

A. 1.5

B. 1.645

C. 1.75

D. 2.12

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In a two-tailed hypothesis test the critical Z is determined to be -2.5. The p-value for this test is

Select one:

A. -1.25

B. 0.4938

C. 0.0062

D. 0.0124

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A student claims that the average grade on the final examination in statistics is going to be at least 85. Another student plans on taking a sample to test the other student's claim. The correct set of hypotheses is

Select one:

A. H0: μ < 85Ha: μ 85

B. H0: μ 85Ha: μ > 85

C. H0: μ 85Ha: μ < 85

D. H0: μ > 85Ha: μ 85

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In order to determine whether or not a driver's education course improves the scores on a driving exam, a sample of 6 students were given the exam before and after taking the course. The results are shown below. Let d = Score After - Score Before.

Student / Score
Before the Course / Score
After the Course
1 / 83 / 87
2 / 89 / 88
3 / 93 / 91
4 / 77 / 77
5 / 86 / 93
6 / 79 / 83

Use = 0.1 and test to see if taking the course actually increased scores on the driving exam. The value of the test statistic is found to be equal to 1.3912. What statement can made about the null hypothesis?

Select one:

A. Reject null hypothesis

B. Fail to reject null hypothesis

C. There is not enough information to make any statement about the null hypothesis

D. None of the above answers is correct

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The following data presents the number of computer units sold per day by a sample of 6 salespersons before and after a bonus plan was implemented.

Salesperson / Before / After
1 / 3 / 6
2 / 7 / 5
3 / 6 / 6
4 / 8 / 7
5 / 7 / 8
6 / 9 / 8

At 95% confidence, test to see if the bonus plan was effective. That is, did the bonus plan actually increase sales? If test statistic for this problem is equal to zero, what conclusion can be drawn?

Select one:

A. Reject null hypothesis, the bonus plan inceased sales

B. Fail to reject null hypothesis, the bonus plan inceased sales

C. Reject null hypothesis, the bonus plan did not inceased sales

D. Fail to reject null hypothesis, the bonus plan did not inceased sales

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Independent samples are obtained from two normal populations with equal variances in order to construct a confidence interval estimate for the difference between the population means. If the first sample contains 16 items and the second sample contains 36 items, the correct form to use for the sampling distribution is the

Select one:

A. normal distribution

B. t distribution with 15 degrees of freedom

C. t distribution with 35 degrees of freedom

D. t distribution with 50 degrees of freedom

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It is believed that people who live in northern Illinois are less likely to return sweepstakes entries than people who live in southern Illinois. Three hundred sweepstakes entries were sent to people in northern Illinois, and 300 entries were sent to people in southern Illinois. Fifty-four percent of the people in northern Illinois return the entries, and 50% of the people in southern Illinois returned the entries. Give a point estimate for the standard deviation of the difference between the population proportions for the two regions.

Select one:

A. 0.0108

B. 0.0208

C. 0.0308

D. 0.0408

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A two-tailed test is performed at 95% confidence. The p-value is determined to be 0.09. The null hypothesis

Select one:

A. must be rejected

B. should not be rejected

C. could be rejected, depending on the sample size

D. has been designed incorrectly

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The daily production rates for a sample of factory workers before and after a training program are shown below.

Worker / Before / After
1 / 6 / 9
2 / 10 / 12
3 / 9 / 10
4 / 8 / 11
5 / 7 / 9

At 95% confidence, test to see if the training program was effective. That is, did the training program actually increase the production rates? State the null and alternative hypotheses.

Select one:

A. Ho: d 0
Ha: d > 0

B. Ho: d 0
Ha: d <0

C. Ho: d = 0
Ha: d 0

D. None of the above

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Independent random samples taken on two university campuses revealed the following information concerning the average amount of money spent on textbooks during the fall semester.

University A / University B
Sample Size / 50 / 40
Average Purchase / $280 / $250
Standard Deviation / $20 / $23

At = .05, test to determine if, on the average, students at University A spend more on textbooks then the students at University B. What is(are) the critical value(s) of the test statistic?

Select one:

A. -1.96

B. 1.665

C. 1.991

D. -1.32 and 1.32

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The office of records at a university has stated that the proportion of incoming female students who major in business has increased. A sample of female students taken several years ago is compared with a sample of female students this year. Results are summarized below. Has the proportion increased significantly? Test at alpha = .10.

Sample Size / No. Majoring in Business
Previous Sample / 250 / 50
Present Sample / 300 / 69

State the null and alternative hypotheses.

Select one:

A. Ho: P1 - P2 = 0
Ha: P1 - P2 0

B. Ho: P1 - P2 0
Ha: P1 - P2 < 0

C. Ho: P1 - P2 0
Ha: P1 - P2 > 0

D. None of the above answers is correct

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n = 49 / = 54.8 / = 28 / H0: μ = 50
Ha: μ 50

If the test is done at the 5% level of significance, the null hypothesis should

Select one:

A. not be rejected

B. be rejected

C. Not enough information given to answer this question.

D. None of these alternatives is correct.

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In hypothesis testing if the null hypothesis is rejected,

Select one:

A. no conclusions can be drawn from the test

B. the alternative hypothesis is true

C. the data must have been accumulated incorrectly

D. the sample size has been too small

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A credit company wants to see if there is any difference in the average amount owed by people under 30 years old and by people over 30 years. Independent random samples of five were taken from both age groups. It can be assumed that the population variances are the same. You are given the following information on the samples.

Amount Owed
Under 30 / Over 30
250 / 800
0 / 500
500 / 0
1,500 / 700
750 / 750

State the null and alternative hypotheses for a two-tailed test.

Select one:

A. Ho: 1 - 2 0. Ha: 1 - 2 > 0.

B. Ho: 1 - 2 0. Ha: 1 - 2 < 0.

C. Ho: 1 - 2 = 0. Ha: 1 - 2 0.

D. None of the above answers is correct