This practice exam consists of 25 multiple choice questions and is similar (in format, types of questions, etc.) to the exam you will take for credit. The time limit for all module exams is 2 hours. It is recommended that you take this practice exam under exam conditions in order to prepare for the module exam. When you are finished with the exam you can check your answers by clicking here.  The module exams are worth 100 points (4 points per question).
 

The next question refers to the following situation.  As part of the National Health Survey, data were collected on the weights of men.  For 804 men aged 25-34, the mean was 176 lb and the standard deviation was 35 lb.  For 1657 men aged 65-74, the mean and standard deviation were 164 lb and 27 lb respectively.

1.)  Which of the following is a 90% confidence interval for the true difference between the means of the men in the two age brackets?

a. (9.69, 14.31)
b. (8.77, 15.23)
c. (10.60, 13.40)
d. (10.28, 13.72)
e. (11.60, 12.40)
 

The next two questions refer to the following situation.  A food company wishes to determine whether the application of a new film to the standard packaging material increases the length of time that potato chips remain fresh.  A random sample of packages with the standard packaging material was compared to an independent random sample of packages with the newly enhanced packaging material.  Summary statistics pertaining to the number of days the chips remained fresh are as follows.  Assume a significance level of a = 0.05.
 

Standard (S)	Enhanced (E)
n1 = 15	n2 = 15
1 = 20.8	2 = 24.2
s1 = 2.8	s2 = 2.5

2.) What are the appropriate hypotheses for this situation?

a.  H₀:  p_S = p_E vs. H_a:  p_S p_E
b.  H₀:  m_S =m_E vs. H_a: m_S > m_E
c.  H₀:  p_S = p_E vs. H_a:  p_S > p_E
d.  H₀:  m_S = m_E vs. H_a: m_Sm_E
e.  H₀:  m_S = m_E vs. H_a: m_S < m_E

3.) What is the absolute value of the appropriate test statistic for this test?

a.  1.32
b.  4.96
c.  2.64
d.  3.51
e.  1.70
 

The next question refers to the following situation.  The Lose Angeles Times polled Californians to learn whether they felt the state government was on the right track in terms of economic and social service programs (Business Week, December 30, 1991). In May of 1991, 600 of 2000 respondents felt the state was on the right track. In December of 1991, 360 of 2000 respondents felt the state was on the right track.

4.)  What is a 90% confidence interval for the true difference in proportions of people who think the state is on the right for the months of May and December?

a. (0.103, 0.137)
b. (0.077, 0.163)
c. (0.098, 0.142)
d. (0.107, 0.133)
e. (0.110, 0.130)
 

The next two questions refer to the following situation.  A study was made of 147 industrial accidents that required medical attention.  Among those accidents, 31 occurred on Monday, 42 on Tuesday, 18 on Wednesday, 25 on Thursday, and 31 on Friday (based on results from "Counted Data CUSUM's," by Lucas, Technometrics, Vol. 27, No. 2).  Investigators want to know if accidents occur with equal proportions on the five workdays (i.e. at a rate of 0.20 for each day).  You can assume a 0.10 level of significance for the test.

5.)  What is the value of the appropriate test statistic for this situation?

a. 2.13
b. 10.65
c. 7.779
d. 9.236
e. 29.4

6.)  What are the rejection region and conclusion for this test, respectively?

a. Reject H₀ if c² < 7.779, Fail to reject H₀
b. Reject H₀ if c² > 2.13, Fail to reject H₀
c. Reject H₀ if c² < 29.4, Reject H₀
d. Reject H₀ if c² > 7.779, Reject H₀
e. Reject H₀ if c² < 9.9236, Reject H₀
 

The next question refers to the following situation.  For a special pre-New Year's Eve show, a radio station personality randomly selected five prominent local citizens to help demonstrate to the listeners the adverse effect of alcohol on reaction time. The reaction times are as follows with summary data also given.

7.)  What is a 99% interval estimate for the true difference between mean reaction time after drinking and before drinking?

a. (0.053, 0.131)
b. (0.032, 0.152)
c. (0.090, 0.094)
d. (0.036, 0.148)
e. (0.023, 0.161)
 

The next two questions refer to the following situation. An investigator studied the proportion of radio listeners who prefer country music. In region A, 56 of the 400 listeners surveyed indicated a preference for country music. In region B, country music was preferred by 95 of the 250 listeners surveyed. At the a = 0.01 level of significance, is there any evidence to suggest that region A has a smaller proportion of listeners who prefer country music?

8.) What are the appropriate hypotheses for this situation?

a. H₀: p_A = p_B vs. H_a: p_A < p_B
b. H₀: p_A = p_B vs. H_a: p_A p_B
c. H₀: m_A = m_B vs. H_a: m_A > m_B
d. H₀: m_A = m_B vs. H_a: m_A m_B
e. H₀: p_A = p_B vs. H_a: p_A > p_B

9.) What is the value of the test statistic and conclusion for this test?

a. -2.33, Fail to Reject H₀
b. -7.04, Reject H₀
c. -3.40, Reject H₀
d. -2.33, Reject H₀
e. -7.04, Fail to Reject H₀
 

The next question refers to the following situation.  Two different car models were tested for fuel economy by determining the miles traveled using 1 gallon of gas.  Independent random samples from each of the models were selected and the following summary statistics were produced.
 
 

Car A	Car B
n1 = 10	n2 = 12
1 = 27.2	2 = 31.6
s1 = 4.1	s2 = 2.1

10.)  What is a 95% interval estimate for the true difference between the mean gas mileage of the two car models?

a. (-6.734, -2.066)
b. (-5.562, -3.238)
c. (-7.052, -1.748)
d. (-5.947, -2.853)
e. (-7.223, -1.577)
 

The next two questions refer to the following situation. A corporate personnel manager is in charge of promoting the "wellness" of employees. One area of opportunity is lowering blood pressure for employees who are reacting to severe stress. The manager wishes to test the effectiveness of a stress-reduction program designed to lower systolic blood pressure. Ten employees with high blood pressure were randomly selected and their blood pressures before and after participating in the stress-reduction program along with some Data Desk output are as follows.

t-Test of Individual µ's
Individual Alpha Level 0.01

Difference: Test Ho: µ(Difference) = 0 vs Ha: µ(Difference) > 0
Sample Mean = 15.90 t-Statistic = ???? w/9 df
p = 0.012

At the a = 0.01 level of significance, is there evidence that suggests the program lowers blood pressure?

11.) What is the value of the appropriate test statistic for this situation?

a. 4.58
b. 0.85
c. 2.82
d. 2.70
e. 3.25

12.) What is the correct conclusion for this test?

a. Reject H₀ since p-value > 0.01
b. Reject H₀ since p-value < 0.01
c. Fail to Reject H₀ since p-value > 0.01
d. Fail to reject H₀ since t > 2.82
e. Reject H₀ since t > 2.82
 

The next two questions refer to the following situation.  In a study of store checkout scanning systems, samples of purchases were used to compare the scanned prices to the posted prices.  The accompanying table summarizes results for a sample of 819 items.  When stores use scanners to check out items, are the error rates the same for regular-priced items as they are for advertised-special items?  Test this hypothesis using an a level of 0.05.
 

13.)  What is the value of the appropriate test statistic for this situation?

a. 2.775
b. 5.991
c. 13.81
d. 7.378
e. 10.81

14.)  What is the correct conclusion for this test?

a. The error rates are not the same since c² > 5.991.
b. The error rates are the same since c² > 5.991.
c. The error rates are not the same since p-value > 0.05.
d. The error rates are the same since c² < 13.81.
e. The error rates are the same since c² > 10.81.
 

The next two questions refer to the following situation.  Students at a particular college randomly selected 217 student cars and found that they had ages with a mean of 7.89 years and a standard deviation of 3.67 years.  They also randomly selected 152 faculty cars and found that they had ages with a mean of 5.99 years and a standard deviation of 3.65 years.  The students want to test the claim that student cars are older than faculty cars.  Assume a 0.05 level of significance.

15.)  What is the value of the test statistic for this situation?

a. 4.91
b. 3.23
c. 1.90
d. 12.69
e. 1.645

16.)  Which one of the following statements is the correct rejection region for the test?

a. Reject H₀ if z > 1.960
b. Reject H₀ if t > 1.960
c. Reject H₀ if |t| < 1.645
d. Reject H₀ if z > 1.645
e. Reject H₀ if |z| > 1.645
 

The next question refers to the following situation.  The New York Times ran an article about a study in which John Hopkins researchers subjected laboratory gloves to stress.  Among 240 vinyl gloves, 63% leaked viruses.  Among 240 latex gloves, 7% leaked viruses.

17.)  What is a 95% interval estimate for the difference between the two proportions of gloves that leak viruses.

a. (0.502, 0.618)
b. (0.491, 0.629)
c. (0.528, 0.592)
d. (0.500, 0.620)
e. (0.513, 0.607)
 

The next two questions refer to the following situation. A meteorologist wants to test for a difference in mean ozone concentrations (in parts per billion) for Maine and Rhode Island. Six recordings were randomly taken for each state. The data was input into Data Desk and Data Desk produced the following output.  Assume an a = 0.05 significance level for this test.

Pooled t-Test of µ1-µ2
Individual Alpha Level 0.05

Ho: µ1-µ2 = 0 Ha: µ1-µ2  0
ME - RI :

Test Ho: µ(ME)-µ(RI) = 0 vs Ha: µ(ME)-µ(RI)  0
Difference Between Means = -1803 t-Statistic = -1.362 w/10 df

18.)  What are the bounds on the true p-value for this test?

a. p-value < 0.01
b. 0.020 < p-value < 0.050
c. 0.025 < p-value < 0.050
d. 0.100 < p-value < 0.200
e. p-value > 0.200

19.) Which one of the following statements is the correct conclusion for the test?

a. There is no difference in ozone concentrations since |t| > 2.228.
b. There is no difference in ozone concentrations since p-value > 0.05.
c. Ozone concentrations in Maine are smaller than those in Rhode Island since p-value < 0.05.
d. There is a difference in ozone concentrations since t < 1.812.
e. Ozone concentrations in Maine are smaller than those in Rhode Island since p-value > 0.05.
 

The next two questions refer to the following situation. A study of seat-belt users and nonusers yielded the following (Data Desk produced) contingency table. The researcher wishes to test the claim that the amount of smoking is independent of seat-belt use with a 0.05 significance level. A plausible theory is that people who smoke more are less concerned about their health and safety and are therefore less inclined to wear seat belts.

Rows are levels of Seatbelt
Columns are levels of Cigarettes
No Selector
                0  1-14  15-34   35+   total

Don't wear    149    17     41     9     216
            -0.28 -0.10   0.31  0.73       0

Wear          175    20     42     6     243
             0.26  0.09  -0.29 -0.69       0

total         324    37     83    15     459
                0     0      0     0       0
table contents:
Count
Standardized Residuals
Chi-square = ???? with 3 df p = 0.7154

20.) What is the value of the appropriate test statistic?

a. 0.030
b. 2.750
c. 1.353
d. 0.715
e. 7.815

21.) Which one of the following statements is the correct conclusion for the test?

a. Seat-belt use is related to smoking since p-value < 0.05.
b. Seat-belt use is not related to smoking since p-value > 0.05.
c. Seat-belt use is related to smoking since the test statistic is larger than 7.815.
d. Seat-belt use is not related to smoking since the test statistic is greater than 0.715.
e. Seat-belt use is related to smoking since p-value > 0.05.
 

The next two questions refer to the following situation. In response to a complaint that a particular tax assessor (A) was biased, an experiment was conducted to compare the assessor named in the complaint with another tax assessor (B) from the same office. Eight properties were randomly selected and each was assessed by both assessors. The assessments (in thousands), the differences, and summary statistics are shown below.

Suppose we wish to test if Assessor A gives higher assessments than Assessor B using an a = 0.05 level of
significance.

22.) What is the value of the test statistic for this situation?

a. 22.59
b. 0.99
c. 2.81
d. 1.48
e. 1.89

23.) Which one of the following statements is the correct conclusion for the test?

a. Assessor A does not give higher assessments since t < 2.3646.
b. Assessor A gives higher assessments since t < 1.8946.
c. Assessor A does not give higher assessments since t < 2.8100.
d. Assessor A gives higher assessments since t > 1.8946.
e. Assessor A gives higher assessments since t < 2.3646.
 

The next two questions refer to the following situation. It is suggested that women differ sharply from men in their preferences for a certain soda. Specifically, 64 of 100 women preferred the soda, whereas 44 of 80 men preferred the soda. Using a significance level of a = 0.10, is there evidence that suggests that the proportions of women and men who prefer the soda are different?

24.) The test statistic value was z = 1.22, what is the p-value for this test?

a. 0.2224
b. 0.3888
c. 0.1944
d. 0.1112
e. 0.0556

25.) What is the correct conclusion for this test?

a. The proportions are not different since p-value < 0.10
b. The proportions are not different since |z| < 1.645
c. The proportions are not different since |z| < 1.28
d. The proportions are different since p-value > 0.10
e. The proportions are different since |z| < 1.645
 

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