Table 1.
n = 49
x = 109.6
s = 28
H0:  = 100
Ha:   100
1.
Refer to Table 1. The test statistic equals
a. 0.34
b. 0.77
c. -2.40
d. 2.40
e. None of the above.
Answer: d
2.
Refer to Table 1. The p-value is equal to
a. 0.000
b. 0.732
c. 0.082
d. 0.016
e. None of the above.
Answer: d
3.
Refer to Table 1. If the test is done at the 5% level of significance, the null hypothesis should
a. not be rejected
b. be rejected
c. neither rejected nor not rejected
d. Not enough information given to answer this question.
e. None of these alternatives is correct.
Answer: b
Table 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 6.2 minutes with a standard deviation of 1 minute. We
want to test to determine whether or not the mean waiting time of all customers is significantly more than 6
minutes.
4.
Refer to Table 2. The test statistic is
a. 1.96
b. 1.64
c. 2.00
d. 0.056
e. None of the above.
Answer: c
5.
Refer to Table 2. The p-value is
a. 0.025
b. 0.0456
c. 0.05
d. 0.0228
e. None of the above.
Answer: d
6.
Refer to Table 2. At 95% confidence, it can be concluded that the mean of the population is
a. significantly greater than 3
b. not significantly greater than 3
c. significantly less than 3
d. significantly greater then 3.18
e. None of the above.
ANSWER: a
Table 3.
A random sample of 100 students is selected. Eighty of the students are women. We are interested in
determining whether or not the proportion of women is significantly more than 75%.
7.
Refer to Table 3. The test statistic is
a. 0.80
b. 0.05
c. 2.00
d. 2.50
e. None of the above.
Answer: e
8.
Refer to Table 3. The p-value is
a. 0.2112
b. 0.05
c. 0.025
d. 0.1056
e. None of the above.
Answer: d
9.
Refer to Table 3. At 95% confidence, it can be concluded that the proportion of the population
who are women
a. is significantly greater than 75%
b. is not significantly greater than 75%
c. is significantly greater than 80%
d. is not significantly greater than 80%
e. None of the above.
Answer: b
Table 4.
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.
10.
Refer to Table 4. The test statistic is
a. 1.96
b. 2.00
c. 1.645
d. 0.05
e. None of the above.
Answer: b
11.
Refer to Table 4. At 95% confidence, it can be concluded that the mean age is
a. not significantly different from 24
b. significantly different from 24
c. significantly less than 24
d. significantly less than 25
e. None of the above.
Answer: b
Table 5.
A random sample of 16 statistics examinations from a large population was taken. The average score in the
sample was 78.6 with a variance of 64. We are interested in determining whether the average grade of the
population is significantly more than 75. Assume the distribution of the population of grades is normal.
12.
Refer to Table 5. The test statistic is
a. 0.45
b. 1.80
c. 3.6
d. 8
e. None of the above.
Answer: b
13.
Refer to Table 5. At 95% confidence, it can be concluded that the average grade of the population
a. is not significantly greater than 75
b. is significantly greater than 75
c. is not significantly greater than 78.6
d. is significantly greater than 78.6
e. None of the above.
Answer: b
Table 6.
Salary information for a random sample of male and female employees of a large company is shown below.
Sample Size
Sample Mean Salary (in $1,000)
Sample Variance
Male
64
88
512
Female
36
82
288
14.
Refer to Table 6. The standard deviation for the difference between the two means is
a. 8.00
b. 14.92
c. 8.48
d. 2.00
e. None of the above.
Answer: e
15.
Refer to Table 6. The 95% confidence interval for the difference between the means of the two
populations is
a. 0 to 13.84
b. -4.00 to 4.00
c. -1.96 to 1.96
d. -1.84 to 13.84
e. None of the above.
Answer: d
16.
Refer to Table 6. If you are interested in testing whether or not the average salary of males is
significantly greater than that of females, the test statistic is
a. 2.0
b. 1.5
c. 1.96
d. 1.645
e. None of the above.
Answer: b
17.
Refer to Table 6. The p-value is
a. 0.0668
b. 0.0334
c. 1.336
d. 1.96
e. None of the above.
Answer: a
18.
Refer to Table 6. At 95% confidence, the conclusion is the
a. average salary of males is significantly greater than females
b. average salary of males is significantly lower than females
c. salaries of males and females are equal
d. The answer cannot be determined from the information provided.
e. None of these alternatives is correct.
Answer: e
Table 7.
The following information was obtained from matched samples.
The daily production rates for a sample of workers before and after a training program are shown below.
Worker
1
2
3
4
5
6
7
Before
20
25
27
23
22
20
17
After
22
23
27
20
25
19
18
19.
Refer to Table 7. The null hypothesis to be tested is H0: d = 0. The test statistic is
a. -1.96
b. 1.96
c. 0
d. 1.645
e. None of the above.
Answer: c
20.
Refer to Table 7. Based on the results of question 18, the
a. null hypothesis should be rejected
b. null hypothesis should not be rejected
c. alternative hypothesis should be accepted
d. neither reject nor fail to reject
d. None of these alternatives is correct.
Answer: b
Table 8.
A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics
today and those enrolled five years ago. A sample of final examination scores from students enrolled today
and from students enrolled five years ago was taken. You are given the following results.
Mean
Variance
Sample Size
Today
82
112.5
45
Five Years Ago
88
54
36
21.
Refer to Table 8. The standard deviation of the difference between the means of the two
populations is
a. 12.9
b. 9.3
c. 4
d. 2
e. None of the above.
Answer: d
22.
Refer to Table 8. The 95% confidence interval for the difference between the two population
means is
a. -4.96 to 1.04
b. -3.92 to 3.92
c. -13.84 to 1.84
d. -24.228 to 12.23
e. None of the above.
Answer: e
23.
Refer to Table 8. The test statistic for the difference between the two population means is
a. -.47
b. -.65
c. -1.5
d. -3
e. None of the above.
Answer: d
24.
Refer to Table 8. The p-value for the difference between the two population means is
a. .0014
b. .0028
c. .4986
d. .9972
e. None of the above.
Answer: b
25.
Refer to Table 8. What is the conclusion that can be reached about the difference in the average
final examination scores between the two classes? (Use a 5% level of significance.)
a. There is a statistically significant difference in the average final examination scores between
the two classes.
b. There is no statistically significant difference in the average final examination scores between
the two classes.
c. It is impossible to make a decision on the basis of the information given.
d. There is a difference, but it is not significant.
e. None of the above.
Answer: a
Table 9.
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.
Sample size
Sample mean
Sample standard deviation
Company A
80
$6.75
$1.00
Company B
60
$6.25
$0.95
26.
Refer to Table 9. The test statistic is
a. 0.098
b. 1.645
c. 2.75
d. 3.01
e. None of the above.
Answer: d
27.
Refer to Table 9. The null hypothesis that the two population means are equal
a. should be rejected
b. should not be rejected
c. should be revised
d. neither reject nor fail to reject
e. None of these alternatives is correct.
Answer: a
Table 10.
The following information regarding a dependent variable (Y) and an independent variable (X) is provided.
Y
4
3
4
6
8
X
2
1
4
3
5
28.
Refer to Table 10. The least squares estimate of the Y intercept is
a. 1
b. 2
c. 3
d. 4
e. None of the above.
Answer: b
29.
Refer to Table 10. The least squares estimate of the slope is
a. 1
b. 2
c. 3
d. 4
e. None of the above.
Answer: a
30.
Refer to Table 10. What percentage of the variation in Y is not explained by variations in X?
a. 70.96%
b. 62.5%
c. 37.5%
d. 44.72%
e. None of the above.
Answer: c
31.
Refer to Table 10. At a 5% level of significance, which of the following is true?
a. The intercept is statistically non-zero.
b. The slope coefficient is statistically non-zero.
c. Both the intercept and the slope coefficient are statistically non-zero.
d. Both the intercept and the slope coefficient are statistically indistinguishable from zero.
e. None of the above.
Answer: b
Table 11.
A regression model between sales (Y in thousands of dollars), unit price (X 1 in dollars) and television
advertisement (X2 in dollars) resulted in the following function:
Ŷ = 7 - 3X1 + 5X2
var(Y) = 32.1, var( û ) = 4.5
32.
Refer to Table 11. The coefficient of the unit price indicates that if the unit price is
a. increased by $1 (holding advertising constant), sales are expected to increase by $3
b. decreased by $1 (holding advertising constant), sales are expected to decrease by $3
c. increased by $1 (holding advertising constant), sales are expected to increase by $4,000
d. increased by $1 (holding advertising constant), sales are expected to decrease by $3,000
e. None of the above.
Answer: d
33.
Refer to Table 11. The coefficient of X2 indicates that if television advertising is increased by $1
(holding the unit price constant), sales are expected to
a. increase by $5
b. increase by $12,000
c. increase by $5,000
d. decrease by $2,000
e. None of the above.
Answer: c
34.
Refer to Table 11. What percentage of the variation in sales is explained by variations in unit
price and advertising?
a. 67.9%
b. 86.0%
c. 32.1%
d. 14.0%
e. None of the above.
Answer: b
Table 12.
Below you are given partial regression results based on a sample of 25 observations.
Constant
X1
X2
X3
35.
Coefficient
145.321
25.625
-5.720
0.823
Standard deviation
48.682
9.150
3.575
0.183
Refer to Table 12. The estimated regression equation is
a. Y = 0 + 1X1 + 2X2 + 3X3 + 
b.
c.
Y = 0 + 1X1 + 2X2 + 3X3
Y = 145.321 + 25.625X1 - 5.720X2 + 0.823X3
Y = 48.682 + 9.15X1 + 3.575X2 + 0.183X3
d.
e. None of the above.
Answer: c
36.
Refer to Table 12. The interpretation of the coefficient on X 1 is that
a. a one unit change in X1 will lead to a 25.625 unit change in Y
b. a one unit change in X1 will lead to a 9.150 unit increase in Y when all other variables are
held constant
c. a one unit change in X1 will lead to a 25.625 unit increase in X2 when all other variables are
held constant
d. It is impossible to interpret the coefficient.
e. None of the above.
Answer: e
37.
Refer to Table 12. We want to test whether the parameter 1 is significant. The test statistic
equals
a. 0.357
b. 2.8
c. 14
d. 1.96
e. None of the above.
Answer: b
38.
Refer to Table 12. The t value obtained from the table to test an individual parameter at the 5%
level is
a. 2.06
b. 2.069
c. 2.074
d. 2.080
e. None of the above.
Answer: d
39.
Refer to Table 12. Carry out the test of significance for the parameter 1 at the 5% level. The null
hypothesis should be
a. rejected
b. not rejected
c. revised
d. neither reject nor fail to reject
e. None of these alternatives is correct.
Answer: a
Table 13.
A simple random sample of 43 elements has been selected from a population of size 800. The sample mean
is 500, and the sample standard deviation is 60.
40.
Refer to Table 13. The standard deviation of the mean is
a. 9.2
b. 43.0
c. 2.68
d. 8.9
e. None of the above.
Answer: d
41.
Refer to Table 13. An approximate 95% confidence interval for the population mean is
a. 482.2 to 517.8
b. 440.0 to 560.0
c. 500.0 to 560.0
d. 440.0 to 500.0
e. None of the above.
Answer: a
Table 14.
Simple random sampling has been used to obtain a sample of size 50 from a population of size 500. The
sample proportion was 0.7.
42.
Refer to Table 14. The estimate of the standard deviation of proportion is
a. 0.210
b. 0.700
c. 0.300
d. 0.062
e. None of the above.
Answer: d
43.
Refer to Table 14. An approximate 95% confidence interval for the population proportion is
a. 0.500 to 0.700
b. 0.750 to 0.810
c. 0.576 to 0.824
d. 0.638 to 0.762
e. None of the above.
Answer: c
Table 1.
An automobile manufacturer maintains two assembly lines. A sample of 15 parts from assembly line A has
a variance of 1.2 microns. A sample of 12 parts from assembly line B has a variance of 1.8 microns. The
manufacturer wants to know whether or not the variance from assembly line B is greater than the variance
from assembly line A.
44.
Refer to Table 1. The test statistic is
a. 1.22
b. 1.88
c. 1.91
d. 1.50
e. None of the above.
Answer: d
45.
Refer to Table 1. The p-value is
a.
b.
c.
d.
e.
35.5%
12.7%
23.5%
76.5%
None of the above.
Answer: c