When testing the difference between two dependent population means, the test statistic
is based on a ______________.
A. Pooled variance
B. Standard deviation of the differences
C. Pooled proportion
D. Sum of the population variances
Manufacturers were subdivided into groups by volume of sales. Those with more than
$100 million in sales were classified as large; those from $50 to $100 million as
medium size; and those between $25 and $50 million, and so on. Samples were then
selected from each of these groups. What is this type of sampling called?
A. Simple random sampling
B. Stratified random sampling
C. Cluster sampling
D. Systematic sampling
If the critical z value for a hypothesis test equals 2.45, what value of the test statistic
would provide the least chance of making a Type I error?
A. 3.74
B. 10,000
C. 2.46
D. 4.56
Which one of the following is NOT a condition of the binomial distribution?
A. Independent trials
B. Only two outcomes
C. The probability of success remains constant from trial to trial
D. Sampling at least 10 trials
In multiple regression analysis, testing the global null hypothesis that all regression
coefficients are zero is based on __________.
A. A z statistic
B. A t-statistic
C. An F-statistic
D. A binomial distribution
The mean score of a college entrance test is 500; the standard deviation is 75. The
scores are normally distributed. What percent of the students scored below 320?
A. About 50.82%
B. About 34.13%
C. About 7.86%
D. About 0.82%
If a student places in the 99th percentile on an exam, she performed better than 99% of
all students who completed the exam. Her performance is similar to a statement based
on a __________.
A. Frequency table
B. Cumulative frequency distribution
C. Histogram
D. Pie chart
A local company wants to evaluate their quality of service by surveying their
customers. Their budget limits the number of surveys to 100. What is their maximum
error of the estimated mean quality for a 95% level of confidence and an estimated
standard deviation of 5?
A. 0.9604
B. 0.98
C. 1.96
D. 5%
Suppose 1,600 of 2,000 registered voters sampled said they planned to vote for the
Republican candidate for president. Using the 0.95 degree of confidence, what is the
interval estimate for the population proportion (to the nearest 10th of a percent)?
A. 78.2% to 81.8%
B. 69.2% to 86.4%
C. 76.5% to 83.5%
D. 77.7% to 82.3%
A telemarketing firm is monitoring the performance of its employees based on the
number of sales per hour. One employee had the following sales for the last 20 hours.
Draw a dot plot for the data.
The distribution of Student’s t is ________.
A. Symmetrical
B. Negatively skewed
C. Positively skewed
D. A discrete probability distribution
A firm offers routine physical examinations as part of a health service program for its
employees. The exams showed that 8% of the employees needed corrective shoes, 15%
needed major dental work, and 3% needed both corrective shoes and major dental work.
What is the probability that an employee selected at random will need either corrective
shoes or major dental work?
A. 0.20
B. 0.25
C. 0.50
D. 1.00
The general process of gathering, organizing, summarizing, analyzing, and interpreting
data is called ____________.
A. Statistics
B. Descriptive statistics
C. Inferential statistics
D. Levels of measurement
The times (in minutes) that several underwriters took to review applications for similar
insurance coverage are 50, 230, 52, and 57. What is the median length of time required
to review an application?
A. 54.5
B. 141.0
C. 97.25
D. 109.0
A company’s headquarters is located in downtown Chicago. If they require their
employees to start working at 6:00 a.m., the company is interested to know the mean
driving time of its employees. Fifty employees are randomly sampled over four weeks
and asked to record their driving times. The mean driving time is 35 minutes, with a
standard deviation of 10 minutes. What is the 98% confidence interval for the
population mean?
For a null hypothesis, H0: = 4,000, if the 1% level of significance is used and the z-test
statistic is +6.00, what is our decision regarding the null hypothesis?
A. Do not reject H0.
B. Reject H0.
C. Reject H1.
D. None Apply.
The members of each basketball team wear numbers on their jerseys. What scale of
measurement are these numbers considered?
A. Nominal
B. Ordinal
C. Interval
D. Ratio
What is another name for the alternate hypothesis?
A. Null hypothesis
B. Hypothesis of no difference
C. Rejected hypothesis
D. Research hypothesis
If the decision is to reject the null hypothesis of no difference between two population
proportions at the 5% level of significance, what are the alternative hypothesis and
rejection region?
A. H1: π1 ≠ π2; z > +1.645 and z < -1.645
B. H1: π1 ≠ π2; z > +1.960 and z < -1.960
C. H1: π1 > π2; z < -1.645
D. H1: π1 > π2; z < -1.960
It is claimed that in a bushel of peaches, less than 10% are defective. A sample of 400
peaches is examined and 50 are found to be defective. What is the sample proportion?
A. 0.10
B. 0.125
C. 40
D. 0.40
The mean of all possible sample means is equal to ____________.
A. The population variance
B.
C. The sample variance
D. The population mean
The mean weight of trucks traveling on a particular section of I-475 is not known. A
state highway inspector needs an estimate of the population mean. He selects and
weighs a random sample of 49 trucks and finds the mean weight is 15.8 tons. The
population standard deviation is 3.8 tons. What is the 95% confidence interval for the
population mean?
A. 14.7 and 16.9
B. 13.2 and 17.6
C. 10.0 and 20.0
D. 16.1 and 18.1
The standard normal probability distribution is unique because it has _________.
A. A mean of 1 and any standard deviation
B. Any mean and a standard deviation of 1
C. A mean of 0 and any standard deviation
D. A mean of 0 and a standard deviation of 1
Refer to the following distribution of commissions:
What is the class interval?
A. 200
B. 300
C. 3,500
D. 400
A group of 100 students was surveyed about their interest in a new International Studies
program. Interest was measured in terms of high, medium, or low. In the study, 30
students responded high interest, 40 students responded medium interest, and 30
students responded low interest. What is the relative frequency of students with high
interest?
A. .30
B. .50
C. .40
D. .030
It is claimed that in a bushel of peaches, less than 10% are defective. A sample of 400
peaches is examined and 50 are found to be defective. What is the p-value?
A. 0.0250
B. 0.4525
C. 0.9525
D. 0.0500
To evaluate the assumption of linearity, a multiple regression analysis should include
___________.
A. A calculation of variance inflation factors
B. Hypothesis tests of individual regression coefficients
C. Scatter diagrams of the dependent variable plotted as a function of each independent
variable
D. An ANOVA table
The number of trials and the population proportion are respectively represented by what
symbols?
A. p and n
B. α and β
C. z and t
D. n and π
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 90 or higher?
A. 0.4979
B. 0.0021
C. 0.9979
D. 2.86
A random sample of 40 companies with assets over $10 million was surveyed and
asked to indicate their industry and annual computer technology expense. The ANOVA
comparing the average computer technology expense among three industries rejected
the null hypothesis. The Mean Square Error (MSE) was 195. The following table
summarized the results:
When comparing the mean annual computer technology expense for companies in the
education and tax services industries, the following 95% confidence interval can be
constructed: _______________.
A. 13.5 2.026 * 5.78
B. 13.5 2.021 * 5.78
C. 13.5 2.026 * 13.96
D. 13.5 2.021 * 13.96
The joint probability of two independent events, A and B, is computed as P(A and B) =
P(A) P(B).
A personnel manager is concerned about absenteeism. She decides to sample employee
records to determine if absenteeism is distributed evenly throughout the six-day
workweek. The null hypothesis is: Absenteeism is distributed evenly throughout the
week. The 0.01 level is to be used. The sample results are:
What is the critical value of chi-square with α = 0.05?
A. 11.070
B. 12.592
C. 13.388
D. 15.033
A financial planner wants to compare the yield of income and growth mutual funds.
Fifty thousand dollars is invested in each of a sample of 35 income and 40 growth
funds. The mean increase for a two-year period for the income funds is $900. For the
growth funds, the mean increase is $875. Income funds have a sample standard
deviation of $35; growth funds have a sample standard deviation of $45. Assume that
the population standard deviations are equal. At the 0.05 significance level, is there a
difference in the mean yields of the two funds?
What is the null hypothesis?
In a one-way ANOVA, the degrees of freedom associated with the error sum of squares
is __________.
A company compared the variance of salaries for employees who have been employed
for 5 years or less with employees who have been employed for 10 years or more. They
randomly selected 21 employees with 5 years or less experience and 15 employees with
10 years or more experience. The standard deviation for the group with 5 years or less
experience was $2,225; the standard deviation for the group with 10 years or more
experience was $1,875. Using the 0.05 significance level, what is the F critical value
for the hypothesis test?
When testing the null hypothesis that two population means are equal, the hypothesized
difference between the population means is ________________.
The lowest level of measurement for a chi-square goodness-of-fit test is the
______________ level.
Making generalized statements about a population based on sample information is
called _________________.
A multiple regression analysis showed the following results of the individual
independent variables.
In stepwise regression, which independent variable would most likely be added first?
A study by a bank compared the average savings of customers who were depositors for
three years or less, with those who had been depositors for more than three years. The
results of a sample are:
What is the computed test statistic? Round to two decimal places.
A z-value measures the distance between an outcome, x, and its population mean in
terms of the number of _____________________.
The waiting time for patients at a local walk-in health clinic follows a normal
distribution with a mean of 15 minutes and a population standard deviation of 5
minutes. The quality-assurance department sampled 50 patients and found that the mean
waiting time was 14.25 minutes. What is the test statistic?
A multiple regression analysis showed the following results of the individual
independent variables.
Which independent variables are significantly related to the dependent variable?