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Consider the following results for two samples randomly taken from two populations.

	Sample A	Sample B
Sample Size	16	10
Sample Mean	28,000	24,000
Sample Standard Deviation	2,100	2,800

Determine the pooled estimate of the population variance.

Select one:

A. 5,696,250.0

B. 5,326,250.0

C. 625.0

D. None of the above answers is correct

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n = 36		= 24.06		S = 12		H0: μ 20
						Ha: μ > 20

The p-value is

Select one:

A. 0.5107

B. 0.0214

C. 0.025

D. -0.025

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Question 3

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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? If test statistic is equal to 5.8, what would be the conclusion?

Select one:

A. Reject null hypothesis, the production rate hasn't increased

B. Fail to reject null hypothesis, the productionrate hasn't increase

C. Reject null hypothesis, the production rate has increase

D. Fail to rejct null hypothesis, production rate has increases

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An official of a large national union claims that the fraction of women in the union is not significantly different from one-half. Using the sample information reported below, carry out a test of this statement. Use a .05 level of significance. State the appropriate null and alternative hypothesis.

sample size		400
women		168
men		232

Select one:

A. H0: P = 0.5 Ha: P 0.5

B. H0: P 0.5 Ha: P < 0.5

C. H0: P 0.5 Ha: P > 0.5

D. None of the above answers is correct

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A student believes that no more than 20% (i.e., 20%) of the students who finish a statistics course get an A. A random sample of 100 students was taken. Twenty-four percent of the students in the sample received As. If test of hypothesis should be conducted at 1% level of significance. What is(are) the cirtical value(s) of the test statistic?

Select one:

A. 1.96

B. -2.33

C. 2.33

D. -1.64 and 1.64

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Question 6

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Independent random samples taken at two local malls provided the following information regarding purchases by patrons of the two malls.

	Hamilton Place	Eastgate
Sample Size	80	75
Average Purchase	$43	$40
Standard Deviation	$ 8	$ 6

At 95% confidence, test to determine whether or not there is a significant difference between the average purchases by the patrons of the two malls. If null hypothesis is rejected, which of the following statements is correct?

Select one:

A. Average purchase at Eastgate is more than Hamilton place average

B. Average purchase at Eastgate is less than Hmailton place average

C. Average purchase at Eastgate is different than Hamilton place average

D. There is not enough information t answer this question

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A school administrator believes that there is no difference in the student dropout rate for schools located in his district and schools located in another district. A random sample of 25 schools in the administrator's district was taken. The student dropout rate of the schools in the sample was 24%. A random sample of 30 schools in the other district had a dropout rate of 27%. Give a point estimate of the standard deviation for the difference between the population proportions for the two districts.

Select one:

A. 0.0128

B. 0.0532

C. 0.0871

D. 0.1178

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Question 8

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To determine the effectiveness of a new weight control diet, ten randomly selected students observed the diet for 4 weeks with the results shown below.

Dieter	Weight Before	Weight After
A	138	135
B	151	147
C	129	132
D	125	127
E	168	155
F	139	131
G	152	144
H	140	142
I	137	137
J	180	180

Set up the null and alternative hypotheses to see if this diet is effective based on defining d as the weight after minus weight before.

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 answers is corret

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Question 9

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

Male Female

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

Refer to Exhibit 10-1. The standard error for the difference between the two means is

Select one:

A. 4

B. 7.46

C. 4.24

D. 2.0

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Question 10

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A random sample of 16 students selected from the student body of a large university had an average age of 25 years and a standard deviation of 2 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. The standardized test statistic is

Select one:

A. 1.96

B. 2.00

C. 1.645

D. 0.05

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n = 16		= 75.6069		s = 8.246		H0: μ 80
						Ha: μ < 80

The p-value is equal to

Select one:

A. -0.025

B. 0.05

C. 0.525

D. 0.025

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Question 12

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For a two-tailed test at 98.4% confidence, Critical Z =

Select one:

A. +1.96

B. +1.14

C. +2.41

D. +0.8612

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Question 13

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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 with a standard deviation of 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 standardized test statistic is

Select one:

A. 1.96

B. 1.64

C. 2.00

D. 0.056

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Question 14

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The following information was obtained from independent random samples. Assume normally distributed populations with equal variances.

	Sample 1	Sample 2
Sample Mean	45	42
Sample Variance	85	90
Sample Size	10	12

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

Select one:

A. 0

B. 2

C. 3

D. 15

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Question 15

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At a local university, a sample of 49 evening students was selected in order to determine whether the average age of the evening students is significantly different from 21. The average age of the students in the sample was 23 with a standard deviation of 3.5. Determine whether or not the average age of the evening students is significantly different from 21. Use a 0.1 level of significance.

Select one:

A. H0: μ 21 Ha: μ < 21

B. H0: μ 21 Ha: μ > 21

C. H0: μ = 21 Ha: μ 21

D. None of the above answers is correct

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Question 16

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

Male Female

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

If you are interested in testing whether or not the average salary of males is significantly greater than that of females, The p-value is

Select one:

A. 0.0668

B. 0.0334

C. 1.336

D. 1.96

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Question 17

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A soft drink filling machine, when in perfect adjustment, fills the bottles with 12 ounces of soft drink. Any overfilling or under filling results in the shutdown and readjustment of the machine. To determine whether or not the machine is properly adjusted, the correct set of hypotheses is

Select one:

A. H0: μ < 12Ha: μ 12

B. H0: μ 12Ha: μ > 12

C. H0: μ 12Ha: μ = 12

D. H0: μ = 12Ha: μ 12

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Question 18

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Independent simple random samples are taken to test the difference between the means of two populations. The sample sizes are n1 = 32 and n2 = 40. The sampling distribution of ( 1 - 2) is the

Select one:

A. normal distribution

B. t distribution with 72 degrees of freedom

C. t distribution with 70 degrees of freedom

D. chi-square distribution

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Question 19

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A lathe is set to cut bars of steel into lengths of 6 centimeters. The lathe is considered to be in perfect adjustment if the average length of the bars it cuts is 6 centimeters. A sample of 121 bars is selected randomly and measured. It is determined that the average length of the bars in the sample is 6.08 centimeters. Assume the population standard deviation is 0.44 centimeters. Use a .05 level of significance. What is the value of test statistic?

Select one:

A. Z = 2

B. t = 2

C. Z = 2.5

D. t = 2.5

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Question 20

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Select one:

A. 0.1123

B. 0.1234

C. 0.1587

D. 0.3413

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Question 21

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In order to determine whether or not there is a significant difference between the hourly wages of two companies, the following data have been accumulated.

	Company A	Company B
Sample size	80	60
Sample mean	$6.75	$6.25
Sample standard deviation	$1.0	$0.95

A point estimate for the difference between the two sample means is

Select one:

A. 20

B. 0.50

C. 0.25

D. 1.00

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Question 22

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If we are interested in testing whether the mean of population 1 is smaller than the mean of population 2, the

Select one:

A. null hypothesis should state μ1 - μ2 < 0

B. null hypothesis should state μ1 - μ2 > 0

C. alternative hypothesis should state μ1 - μ2 > 0

D. alternative hypothesis should state μ1 - μ2 < 0

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Question 23

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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. What is the p-value associated with the sample results?

Select one:

A. p-value = 0.1587

B. p-value = 0.3413

C. p-value = 0.1134

D. p-value = 0.0921

E. None of the above answer is correct

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Question 24

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In hypothesis testing if the null hypothesis has been rejected when the alternative hypothesis has been true,

Select one:

A. a Type I error has been committed

B. a Type II error has been committed

C. either a Type I or Type II error has been committed

D. the correct decision has been made

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Question 25

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In the hypothesis testing procedure, is

Select one:

A. the level of significance

B. the critical value

C. the confidence level

D. 1 - level of significance

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