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6.A grouped frequency distribution has a mean of 100 and a standard deviation of 20. The class limits for one class are 15 and 25. What are the standard normal z-statistics for the class limits?

-20.0 and 20.0.

-4.25 and -3.75

-15.0 and -5.0

3.75 and 4.25

7 A random sample of 32 companies was selected and asked for their annual dividend rate in three different industries: utilities, banking, and insurance. The ANOVA comparing the mean annual dividend rate among three industries rejected the null hypothesis. The Mean Square Error (MSE) was 3.36. The following table summarized the results:

Utilities Banking Insurance

Number sampled 10 10 12

Mean annual dividend rate 22.11 15.4 22.2

When comparing the mean annual dividend rate for companies in the utilities and insurance industries, the following 95% confidence interval can be constructed:

0.09 ± 2.179 * 1.57

0.09 ± 2.045 * 0.78

0.09 ± 2.179 * 0.78

0.09 ± 2.045 * 1.57

8 A recent study focused on the number of times men and women send a Twitter message in a day. The information is summarized below.

Sample Size Sample Mean Population Standard

Deviation

Men 24 19 11

Women 38 38 22

At the .01 significance level, is there a difference in the mean number of times men and women send a Twitter message in a day? What is the p-value for this hypothesis test?

0.0750

0.0000

0.0250

0.7500

A sales manager for an advertising agency believes that there is a relationship between the number of contacts that a sales person makes and the amount of the sales dollars earned.

A regression analysis shows the following results:

Coefficients Standard Error t Stat P-value

Intercept 4.799 6.530 0.735 0.500

Number of Contacts 2.280 0.155 14.710 0.000

ANOVA

df SS MS F Significance F

Regression 1.00 13,650.94 13,650.94 485.97 0.00

Residual 25.00 702.32 28.09

Total 26.00 14,353.26

formula32.mml

The 90% prediction interval for a particular person making 13 calls is

24.93, 43.95

7.37, 1.50

7.63, 16.50

7.37, 31.50

The claim that “40% of those persons who retired from an industrial job before the age of 60 would return to work if a suitable job was available” is to be investigated at the 0.02 significance level. If 74 out of the 200 workers sampled said they would return to work, what is our decision?

Do not reject the null hypothesis because -0.879 lies in the region between +2.5760 and -2.576.

Do not reject the null hypothesis because 37% lies in the area between 0% and 40%.

Do not reject the null hypothesis because -0.879 lies in the region between +2.326 and -2.326.

Reject the null hypothesis because 37% is less than 40%.

What are the two critical values for a two-tailed test with a 0.01 level of significance when n is large and the population standard deviation is known?

Above 2.58 and below -2.58

Above 0.68 and below -0.68

Above 2.26 and below -2.26

Above 1.00 and below -1.00

Two samples, one of size 15 and the second of size 13, are selected to test the difference between two population means. How many degrees of freedom are used to find the critical value? Assume the population standard deviations are equal.

15

25

28

27

26

A hypothesis regarding the weight of newborn infants at a community hospital is that the mean is 11.3 pounds. A sample of seven infants is randomly selected and their weights at birth are recorded as 9.0, 7.3, 6.0, 8.8, 6.8, 8.4, and 11.3 pounds. The null hypothesis is

H0: µ = 11.3

H0: µ > 12.3

H0: µ ≥ 11.3

H0: µ ≤ 12.3

21 The annual dividend rates for a random sample of 16 companies in three different industries, utilities, banking, and insurance were recorded. The ANOVA comparing the mean annual dividend rate among three industries rejected the null hypothesis that the dividend rates were equal. The Mean Square Error (MSE) was 3.36. The following table summarized the results:

Picture

Based on the comparison between the mean annual dividend rate for companies in utilities and banking, the 95% confidence interval shows an interval of 1.28 to 6.28 for the difference. This result indicates that _____________________.

The annual dividend rate in the banking industry is significantly less than the annual dividend rate in the utilities industry

The interval contains a difference of 5.00

There is no significant difference between the two rates

The annual dividend rate in the utilities industry is significantly less than the annual dividend rate in the banking industry

23 the regression equation is Ŷ = 30 + 2.56X, the sample size is 14, and the standard error of the slope is 0.97. What is the test-statistic to test the significance of the slope?

z = +2.639

t = +2.560

z = -2.560

t = +2.639

50 Given the following Analysis of Variance table for three treatments each with six observations.

Source Sum of Squares df Mean Square

Treatments 1,182

Error 1,042

Total 2,224

What is the computed value of F?

8.51

9.70

9.49

7.94

49 A grouped frequency distribution has a mean of 100 and a standard deviation of 20. The class limits for one class are 50 and 60. Based on the normal distribution, what is the probability that an observation would be in this class?

0.2272

0.0165

-0.0165

0.4938

47 A sample of 250 adults tried the new multigrain cereal “Wow!” A total of 187 rated it as excellent. In a sample of 100 children, 66 rated it as excellent. Using the 0.1 significance level, the researcher wishes to show that adults like the cereal better than children. What is the pooled proportion?

0.494

1.408

0.807

0.723

46 The average cost of tuition, room and board at small private liberal arts colleges is reported to be $8,500 per term, but a financial administrator believes that the average cost is higher. A study conducted using 350 small liberal arts colleges showed that the average cost per term is $8,745 with a standard deviation of $1,200. Let formula4.mml = 0.13. What is the critical z-value for this test?

-1.44

+1.44

+1.13

-1.13

45 For a hypothesis comparing two population means, what is the critical value for a one-tailed hypothesis test, using a 5% level of significance level, with both sample sizes equal to 18? The standard deviations for the samples are 16 and 18. Assume the population standard deviations are unequal.

2.192

1.742

1.692

1.269

To test the hypothesis that 55% of those families who plan to purchase a vacation residence in Florida want a condominium, the null hypothesis is π = 0.55 and the alternate is π ≠ .55. A random sample of 400 families who planned to buy a vacation residence revealed that 228 families want a condominium. What decision should be made regarding the null hypothesis using the 0.01 level of significance?

Reject it.

Do not reject it.

Purchase a condominium.

To test the hypothesis that 55% of those families who plan to purchase a vacation residence in Florida want a condominium, the null hypothesis is π = 0.55 and the alternate is π ≠ .55. A random sample of 400 families who planned to buy a vacation residence revealed that 228 families want a condominium. What decision should be made regarding the null hypothesis using the 0.01 level of significance?

Reject it.

Do not reject it.

Purchase a condominium.

Cannot accept it or reject it based on the information given. Cannot accept it or reject it based on the information given.

42 A recent study of the relationship between social activity and education showed the following results.

Social Activity

Education Above Average Average Below Average

College 28 20 8

High School 18 40 106

Grade School 8 50 126

What is the value of the test statistic?

92.58

20.20

5.45

67.33

41 A regression analysis yields the following information:

Picture ; n = 10; sy∙x = 1.66; ΣX = 32; ΣX2 = 134; Picture

Compute the 95% confidence interval when X = 4.

6.842, 9.497

4.15, 12.25

0.0, 4.05

2.67, 5.33

40.value:

2.00 points

Two accounting professors decided to compare the variance of their grading procedures. To accomplish this, they each graded the same 17 exams with the following results:

Mean Grade Standard Deviation

Professor 1 81.5 26.8

Professor 2 88.4 13.9

The calculated F ratio is

5.863

3.717

2.146

1.492

39.value:

2.00 points

A personnel manager is concerned about absenteeism. She decides to sample the records to determine if absenteeism is distributed evenly throughout the six-day workweek. The null hypothesis to be tested is: Absenteeism is distributed evenly throughout the week. The 0.4 level is to be used. The sample results are:

Day of Week Number Absent

Monday 52

Tuesday 69

Wednesday 51

Thursday 30

Friday 69

Saturday 29

How many degrees of freedom are there?

5

4

3

6

37.value:

2.00 points

A regression analysis yields the following information:

formula47.mml

formula48.mml

Compute the 90% prediction interval when X = 6.

10.44, 12.76

10.82, 13.38

8.02, 15.18

5.38, 6.30

36 Several employees have submitted different methods of assembling a subassembly. Sample data for each method are:

Picture

How many treatments are there?

0

12

4

3

35 A hypothesis regarding the weight of newborn infants at a community hospital is that the mean is 6.6 pounds. A sample of seven infants is randomly selected and their weights at birth are recorded as 9.0, 7.3, 6.0, 8.8, 6.8, 8.4, and 6.6 pounds. The null hypothesis is ______.

H0: µ ≥ 6.6

H0: µ = 6.6

H0: µ > 7.6

H0: µ ≤ 7.6

33 A sales manager for an advertising agency believes that there is a relationship between the number of contacts that a sales person makes and the amount of the sales dollars earned.

A regression analysis shows the following results:

Coefficients Standard Error t Stat P-value

Intercept 4.799 6.530 0.735 0.500

Number of Contacts 2.280 0.155 14.710 0.000

ANOVA

df SS MS F Significance F

Regression 1.00 13,650.94 13,650.94 485.97 0.00

Residual 25.00 702.32 28.09

Total 26.00 14,353.26

formula32.mml

The 90% confidence interval for 13 calls is

42.57, 32.57

31.08, 37.80

16.30, 47.30

33.57, 43.57

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