Refer to the following distribution of ages:
What is the class midpoint of the highest class?
A. 54
B. 55
C. 64
D. 65
A random sample of 20 items is selected from a population. When computing a
confidence interval for the population mean, what number of degrees of freedom should
be used to determine the appropriate t-value?
A. 20
B. 19
C. 21
D. 25
The average cost of tuition and room and board at a small private liberal arts college is
reported to be $8,500 per term, but a financial administrator believes that the average
cost is higher. A study conducted using 350 small liberal arts colleges showed that the
average cost per term is $8,745. The population standard deviation is $1,200. Let α =
0.05. What is the critical z value for this test?
A. +1.960
B. -1.960
C. +1.645
D. -1.645
Three different fertilizers were applied to a field of celery. In computing F, how many
degrees of freedom are there in the numerator?
A. 0
B. 1
C. 2
D. 3
A portion or part of a population is called a
A. Random survey
B. Sample
C. Tally
D. Frequency distribution
In a large metropolitan area, past records revealed that 30% of all the high school
graduates go to college. From 20 graduates selected at random, what is the probability
that exactly 8 will go to college?
A. 0.114
B. 0.887
C. 0.400
D. 0.231
An investigation of the effectiveness of a training program to improve customer
relationships included a pre-training and post-training customer survey. To compare the
differences, they computed (post-training survey score – pre-training survey score).
Seven customers were randomly selected and completed both surveys. The results
follow.
This analysis is an example of _____________.
A. A one-sample test of means
B. A two-sample test of means
C. A paired t-test
D. A test of proportions
A sample of wires coming off the production line was tested for tensile strength. The
statistical results (in PSI) were the following:
According to the Empirical Rule, the middle 95% of the wires tested had a tensile
strength between approximately what two values?
A. 450 and 550
B. 460 and 540
C. 420 and 580
D. 380 and 620
A question in a market survey asks for a respondent’s favorite car color. Which measure
of central location should be used to summarize this question?
A. Mode
B. Median
C. Mean
D. Standard deviation
The regression equation is Ŷ = 30 + 2.56X, the sample size is 14, and the standard error
of the slope is 0.97. What is the critical value to test the significance of the slope at the
0.05 significance level?
A. z = 1.96
B. t = 2.179
C. t = 2.145
D. t = +2.145
A preliminary study of hourly wages paid to unskilled employees in three metropolitan
areas was conducted. Seven employees were included from Area A, 9 from Area B, and
12 from Area C. The test statistic was computed to be 4.91. What can we conclude at
the 0.05 level?
A. Mean hourly wages of unskilled employees of all areas are equal.
B. Mean hourly wages in at least two metropolitan areas are different.
C. More degrees of freedom are needed.
D. None of these is correct.
A rug manufacturer has decided to use seven compatible colors in her rugs. However, in
weaving a rug, only five spindles can be used. In advertising, the rug manufacturer
wants to indicate the number of different color groupings for sale. How many color
groupings using the seven colors taken five at a time are there? (This assumes that five
different colors will go into each rugin other words, there are no repetitions of color.)
A. 7
B. 21
C. 840
D. 42
Assume the least squares equation is Ŷ = 10 + 20X. What does the value of 10 in the
equation indicate?
A. When X = 0, Y = 10.
B. X increases by 10 for each unit increase in Y.
C. Y increases by 10, for each unit increase in X.
D. It is the error of estimation.
A group of women tried five brands of fingernail polish and ranked them according to
preference. What level of measurement is this?
A. Nominal
B. Ordinal
C. Interval
D. Ratio
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 Y-intercept of the linear equation?
A. -12.201
B. 2.195
C. -1.860
D. 12.505
A sales representative calls on four hospitals in Westchester County. It is immaterial
what order he calls on them. How many ways can he organize his calls?
A. 4
B. 24
C. 120
D. 37
What is the null hypothesis to test the significance of the slope in a regression equation?
A. H0: β = 0
B. H0: β ≠ 0
C. H0: β ≤ 0
D. H0: β ≥ 0
The best example of a null hypothesis for a global test of a multiple regression model is
_________.
A. H0: β1 = β2 = β3 = β4 = 0
B. H0: 1 = 2 = 3 = 4 = 0
C. H0: β1 = 0
D. If F is greater than 20.00, then reject.
What is the chart called when the paired data (the dependent and independent variables)
are plotted?
A. A scatter diagram
B. A bar chart
C. A pie chart
D. A histogram
A sample distribution of hourly earnings in Paul’s Cookie Factory is:
The limits of the class with the smallest frequency are:
A. $6.00 and $9.00
B. $12.00 and up to $14.00
C. $11.75 and $14.25
D. $12.00 and up to $15.00
Refer to the following breakdown of responses to a survey of room service in a hotel.
What type of chart should be used to show relative class frequencies?
A. A pie chart
B. A bar chart
C. A histogram
D. A frequency polygon
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 two messages?
A. 0.0067
B. 0.0014
C. 0.4200
D. 0.0842
If two events are mutually exclusive, then P(A and B) = P(A)P(B).
Refer to the following breakdown of responses to a survey of room service in a hotel.
What type of chart should be used to describe the frequency table?
A. A pie chart
B. A bar chart
C. A histogram
D. A frequency polygon
The reported unemployment is 5.5% of the population. What measurement scale is used
to measure unemployment?
A. Nominal
B. Ordinal
C. Interval or ratio
D. Descriptive
The sum of the deviations of each data value from this measure of central location will
always be zero.
A. Mode
B. Mean
C. Median
D. Standard deviation
A hypothesis regarding the weight of newborn infants at a community hospital is that
the mean is 6.6 pounds. A sample of seven infants is randomly selected and their
weights at birth are recorded as 9.0, 7.3, 6.0, 8.8, 6.8, 8.4, and 6.6 pounds. What is the
sample mean?
A. 6.6
B. 7.6
C. 1.177
D. 2.447
In stratified random sampling, a population is divided into strata using naturally
occurring geographic or other boundaries. Then, strata are randomly selected and a
random sample is collected from each strata.
A student wanted to construct a 95% confidence interval for the mean age of students in
her statistics class. She randomly selected nine students. Their average age was 19.1
years with a sample standard deviation of 1.5 years. What is the best point estimate for
the population mean?
A. 2.1 years
B. 1.5 years
C. 19.1 years
D. 9 years
A farmer who grows genetically engineered corn is experiencing trouble with corn
borers. A random check of 5,000 ears revealed the following: Many of the ears
contained no borers. Some ears had one borer; A few had two borers, and so on. The
distribution of the number of borers per ear approximated the Poisson distribution. The
farmer counted 3,500 borers in the 5,000 ears. What is the probability that an ear of
corn selected at random will contain no borers?
A. 0.3476
B. 0.4966
C. 1.000
D. 0.0631
The Intelligence Quotient (IQ) test scores for adults are normally distributed with a
mean of 100 and a standard deviation of 15. What is the probability we could select a
sample of 50 adults and find that the mean of this sample is between 98 and 103?
A. 0.3264
B. 0.9428
C. 0.4702
D. 0.7471
Using the following information:
The regression analysis can be summarized as follows:
A. No significant relationship between the variables.
B. A significant negative relationship exists between the variables.
C. A significant positive relationship exists between the variables.
D. For every unit increase in X, Y decreases by 12.8094.
In multiple regression analysis, residuals (Y – Ŷ) are used to _____________.
A. Provide a global test of a multiple regression model
B. Evaluate multicollinearity
C. Evaluate homoscedasticity
D. Compare two regression coefficients
The net weights (in grams) of a sample of bottles filled by a machine manufactured by
Edne, and the net weights of a sample filled by a similar machine manufactured by
Orno, Inc., are:
Testing the claim at the 0.05 level that the mean weight of the bottles filled by the Orno
machine is greater than the mean weight of the bottles filled by the Edne machine, what
is the critical value? Assume equal standard deviations for both samples.
A. +2.179
B. +2.145
C. +1.782
D. +1.761
The degrees of freedom for a chi-square goodness-of-fit test is equal to
______________.
Using the following regression analysis:
What is the residual sum of squares?
For a sampling distribution of the means, _______% of the means would be between
2.58 standard deviations.
An ANOVA showed the following comparison of four treatment means.
Which treatment means are significantly different?
A company’s human resources department was interested in the average number of
years that a person works before retiring. The sample of size 11 follows:
What is the median?
For a binomial distribution, explain why .
A multiple regression analysis showed the following ANOVA table result.
Based on the information in the ANOVA, what is the multiple coefficient of
determination expressed as a percent?
When evaluating the assumptions of a multiple regression model, a _______ is
calculated for every observation in a data set
A research firm conducted a survey to determine the mean amount people spend at a
popular coffee shop during a week. They found the amounts spent per week followed a
normal distribution, with a population standard deviation of $4. A sample of 49
customers revealed that the mean is $25. What is the 95% confidence interval estimate
of ?
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. What is the value of the test statistic?
Twenty-one executives in a large corporation were randomly selected to study the effect
of several factors on annual salary (expressed in $000s). The factors selected were age,
seniority, years of college, number of company divisions they had been exposed to, and
the level of their responsibility. The results of the regression analysis follow:
Which independent variable has the most significant effect on annual salary?
What is the difference between a scatter diagram and a contingency table?
For hypotheses that compare two population means, what test statistic is used when the
population standard deviations are known?
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 gas?