If the correlation coefficient between two variables, X and Y, equals zero, what can be
said of the variables X and Y?
A. The variables are not related.
B. The variables are dependent on each other.
C. The variables are highly related.
D. X causes Y.
If two events are independent, then their joint probability is computed with _________.
A. The special rule of addition
B. The special rule of multiplication
C. The general rule of multiplication
D. The Bayes theorem
A bank asks customers to evaluate the drive-thru service as good, average, or poor.
Which level of measurement is this classification?
A. Nominal
B. Ordinal
C. Interval
D. Ratio
Percentiles divide a distribution into _____________.
A. 2 equal parts
B. 4 equal parts
C. 10 equal parts
D. 100 equal parts
How many permutations of the three letters C, D, and E are possible?
A. 3
B. 0
C. 6
D. 8
The range of the coefficient of skewness is ____________.
A. Values greater than or equal to zero or always positive
B. Values less than or equal to zero or always negative
C. Both positive and negative values
D. Values between -1 and +1
A sales manager for an advertising agency believes that there is a relationship between
the number of contacts that a salesperson makes and the amount of sales dollars earned.
A regression analysis shows the following results:
What is the regression equation?
A. = 2.195 – 12.201X
B. = -12.201 + 2.195X
C. = 12.201 + 2.195X
D. = 2.195 + 12.201X
Based on the Nielsen ratings, the local CBS affiliate claims its 11 p.m. newscast reaches
41% of the viewing audience in the area. In a survey of 100 viewers, 36% indicated that
they watch the late evening news on this local CBS station. What is the null hypothesis?
A. H0: π = 0.36
B. H0: π = 0.41
C. H0: π ≠ 0.36
D. H0: = 0.41
For people released from prison, the following table shows their adjustment to civilian
life and place of residence.
What is the critical value for this contingency table at the 0.01 level of significance?
A. 9.488
B. 2.070
C. 11.345
D. 13.277
The lowest level of measurement that has some sort of ranking is __________.
If the coefficient of determination is 0.94, what can we say about the relationship
between two variables?
A. The strength of the relationship is 0.94.
B. The direction of the relationship is positive.
C. 94% of the total variation of the dependent variable is explained by the independent
variable.
D. The direction of the relationship is negative.
What does the interquartile range describe?
A. The range of the lower 50% of the observations
B. The range of the middle 50% of the observations
C. The range of the upper 50% of the observations
D. The ranges of the lower 25% and the upper 25% of the observations
The following is a binomial probability distribution with n = 3 and π = 0.20.
The mean of the distribution is _______.
A. 1.50
B. 0.60
C. 0.25
D. 0.00
A statistics professor receives an average of five e-mail messages per day from
students. Assume the number of messages approximates a Poisson distribution. What is
the probability that on a randomly selected day she will have five messages?
A. 0.0067
B. 0.8750
C. 0.1755
D. 1.0000
The shape of any uniform probability distribution is ____________.
A. Negatively skewed
B. Positively skewed
C. Rectangular
D. Bell-shaped
Bones Brothers & Associates prepare individual tax returns. Over prior years, Bones
Brothers has maintained careful records regarding the time to prepare a return. The
mean time to prepare a return is 90 minutes and the standard deviation of this
distribution is 14 minutes. Suppose 100 returns from this year are selected and analyzed
regarding the preparation time. What is the probability that the mean time for the
sample of 100 returns for this year is greater than 92?
A. Approximately zero
B. 0.0832
C. 0.4168
D. 0.0764
A statistics professor receives an average of five e-mail messages per day from
students. Assume the number of messages approximates a Poisson distribution. What is
the probability that on a randomly selected day she will have no messages?
A. 0.0067
B. Zero
C. 0.0335
D. Impossible to have no messages
For a relative frequency distribution, relative frequency is computed as
_____________.
A. The class width divided by class interval
B. The class midpoint divided by the class frequency
C. The class frequency divided by the class interval
D. The class frequency divided by the total frequency.
Which of the following are true assumptions underlying linear regression? (1) For each
value of X, there is a group of Y values that is normally distributed. (2) The means of
these normal distributions of Y values all lie on the regression line. (3) The standard
deviations of these normal distributions are equal.
A. Only (1)
B. Only (2)
C. Only (3)
D. All of them
Refer to the following distribution of ages:
For the distribution of ages just shown, what is the relative class frequency for the
lowest class?
A. .50
B. .18
C. .20
D. .10
A national manufacturer of ball bearings is experimenting with two different processes
for producing precision ball bearings. It is important that the diameters be as close as
possible to an industry standard. The output from each process is sampled and the
average error from the industry standard is measured in millimeters. The results are
presented next.
The researcher is interested in determining whether there is evidence that the two
processes yield different average errors. The population standard deviations are
unknown but are assumed equal. This example is what type of test?
A. A one-sample test of means
B. A two-sample test of means
C. A paired t-test
D. A test of proportions
The following correlations were computed as part of a multiple regression analysis that
used education, job, and age to predict income.
What is this table called?
A. Net regression coefficients
B. Coefficients of nondetermination
C. Analysis of variance
D. Correlation matrix
The number of workers calling in sick during any particular week is considered to be
_______________ data.
The true sampling error is usually not known because ________.
A. is unknown
B. is a random variable
C. σ2 is unknown
D. The sample mean cannot be computed
When a class interval is expressed as 100 up to 200, _________________________.
A. Observations with values of 100 are excluded from the class
B. Observations with values of 200 are included in the class
C. Observations with values of 200 are excluded from the class
D. The class interval is 99
Mileage tests were conducted on a randomly selected sample of 100 newly developed
automobile tires. The results showed that the mean tread life was 50,000 miles, with a
standard deviation of 3,500 miles. What is the best estimate of the mean tread life in
miles for the entire population of these tires?
A. 50,000
B. 3,500
C. 500
D. 35
The average score of 100 students taking a statistics final was 70 with a standard
deviation of 7. Assuming a normal distribution, what is the probability that a student
scored greater than 65?
A. 0.2611
B. 0.2389
C. 0.7611
D. -0.714
A pie chart shows the ______________________.
A. Relative frequencies of a qualitative variable
B. Relative frequencies of a quantitative variable
C. Frequencies of a nominal variable
D. Frequencies of a ratio variable
To apply a Poisson probability distribution, the mean can be computed as __________.
A. nπ
B.
C. e-x
D.
The following graph illustrates _______________.
A. A positive or direct relationship
B. A negative or inverse relationship
C. No relationship
D. A distribution for a single variable
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 test statistic should we use to compare the ratings of adults and
children?
A. A z-statistic
B. A right one-tailed test statistic
C. A left one-tailed test statistic
D. A t-statistic
A tire manufacturing company is reviewing its warranty for their rainmaker tire. The
warranty is for 40,000 miles. The distribution of tire wear is normally distributed with a
population standard deviation of 15,000 miles. The tire company believes that the tire
actually lasts more than 40,000 miles. A sample of 49 tires revealed that the mean
number of miles is 45,000 miles. Test the hypothesis with a 0.05 significance level.
What is our decision?
The relationship between interest rates as a percent (X) and housing starts (Y) is given
by the linear equation Ŷ = 4094 – 269X. What will be the number of housing starts if the
interest rate is 8.25%?
The following graph is used to evaluate an assumption of a multiple regression analysis.
What is the assumption?
Using the following regression analysis:
What is the coefficient of determination?
When estimating a population mean with a confidence interval, a smaller margin of
error requires a _________ sample size.
Approximately ______% of the observations lies within two standard errors of the
regression line.
A multiple regression analysis showed the following ANOVA table result.
Based on the information in the ANOVA, what is the multiple coefficient of
determination?
The following graph is used to evaluate two assumptions of a multiple regression
analysis. What are the two assumptions?
A major credit card company has determined that customers charge between $100 and
$1,100 per month. If the average monthly amount charged is uniformly distributed, the
percent of monthly changes between $311 and $889 is _______.
A committee that is studying employer-employee relations proposed that each employee
would rate his or her immediate supervisor, and in turn the supervisor would rate each
employee. To test if the reactions to the survey for office and plant personnel were the
same, 120 office personnel and 160 plant personnel were selected at random.
Seventy-eight of the office personnel and 90 of the plant personnel were in favor of the
proposal. To test the hypothesis that the population proportions are equal, what is the
critical value using the 0.05 level of significance?
A tire manufacturing company is reviewing its warranty for their rainmaker tire. The
warranty is for 40,000 miles. The distribution of tire wear is normally distributed with a
population standard deviation of 15,000 miles. The tire company believes that the tire
actually lasts more than 40,000 miles. A sample of 49 tires revealed that the mean
number of miles is 45,000 miles. To test the hypothesis at a 0.05 significance level,
what is the computed test statistic?
In a multiple regression analysis with five independent variables, the null hypothesis,
H0: β4 = 0, is not rejected. When predicting the dependent variable, the independent
variable, X4, has ______ relationship to the dependent variable.
A sample of five full-service gasoline stations, each carrying three grades of gasoline,
was taken, and the price per liter (to the nearest cent) was recorded for each grade of
gasoline, as shown in the following table.
What is the mean price of unleaded plus gas?
A survey of property owners’ opinions about a street-widening project was taken to
determine if owners’ opinions were related to the distance between their home and the
street. A randomly selected sample of 100 property owners was contacted and the
results are shown next.
What is your decision regarding the null hypothesis at the 5% level of significance?
For the following probability distribution:
The variance is _____________.
The Greek letter _________ is used to represent the probability of making a Type I
error.
The distribution of annual salaries for 52 employees in a small manufacturing company
has the following averages: the mean is $25,459, the median is $24,798 and the mode is
$24,000. What is the total amount paid for employee salaries?
When the population standard deviation is unknown, a __________ statistic is used to
compute a confidence interval.
Contingency table analysis can be used to test for a relationship between two
_________ scale variables.