The local amusement park was interested in the average wait time at their most popular
roller coaster at the peak park time (2 p.m.). They selected 13 patrons and had them get
in line between 2 and 3 p.m. Each was given a stopwatch to record the time they spent
in line. The times recorded were as follows (in minutes;mean = 114.15):
118, 124, 108, 116, 99, 120, 148, 118, 119, 121, 45, 130, 118.
What is the range?
A. 103
B. 23.62
C. 557.97
D. 128.8
E. 115
Suppose that 60 percent of the voters in a particular region support a candidate. Find the
probability that a sample of 1,000 voters would yield a sample proportion in favor of
the candidate within 4 percentage points of the actual proportion.
A. .0155
B. .9952
C. .9484
D. .9902
When applying Bayes Theorem, the sample information is combined with prior
probabilities to obtain ___________________ probabilities.
A. utility
B. maximax
C. posterior
D. preposterior
An environmental group at a local college is conducting independent tests to determine
the distance a particular make of automobile will travel while consuming only 1 gallon
of gas. They test a sample of five cars and obtain a mean of 28.2 miles. Assuming that
the standard deviation is 2.7 miles, find the 95 percent confidence interval for the mean
distance traveled by all such cars using 1 gallon of gas.
A. [26.16, 30.24]
B. [20.70, 35.70]
C. [24.85, 31.55]
D. [26.70, 29.70]
E. [25.83, 30.57]
In order to perform the ________________, all of the observations in p samples are
combined into a single set and all of the values in the single set are ranked from
smallest to largest. After ranking, the sum of the ranks for each of the p samples is
calculated.
A. Wilcoxon rank sum test
B. Kruskal-Wallis H test
C. Wilcoxon signed ranks test
D. sign test
For a binomial process, the probability of success is 40 percent and the number of trials
is 5. Find P(X 1).
A. .0870
B. .2592
C. .0778
D. .3370
The number of standard deviations that a value x is from the mean is a(n)
____________.
A. variance
B. exponential value
C. z score
D. area
Which of the following statements about the binomial distribution is not correct?
A. Each trial results in a success or failure.
B. Trials are independent of each other.
C. The probability of success remains constant from trial to trial.
D. The random variable of interest is continuous.
E. The experiment consists of n identical trials.
New car owners were asked to evaluate their experiences in buying a new car during
the past 12 months. In the survey, the owners indicated they were most satisfied with
their experiences at the following three dealers (in no particular order): Subaru, Honda,
and Buick. Assuming that each set of rankings is equally likely, what is the probability
that owners ranked Subaru first and Honda second?
A. 1/3
B. 1/6
C. 1/2
D. 5/6
E. 6/6
It has been reported that the average time to download the home page from a
government website was 0.9 seconds. Suppose that the download times were normally
distributed with a standard deviation of 0.3 seconds. If random samples of 36 download
times are selected, 80 percent of the sample means will be between what two values
symmetrically distributed around the population mean?
A. [.648, 1.152]
B. [.836, .964]
C. [.514, 1.280]
D. [.858, .942]
The population of all _________________ proportions is described by the sampling
distribution of .
A. population
B. random
C. observed
D. sample
When a ____________ probability distribution is used to approximate a ____________
probability distribution, we must make a ____________ correction.
A. continuous, discrete, continuity
B. discrete, continuous, continuity
C. continuous, discrete, finite population
D. None of the other choices is correct.
Which of the following is a quantitative variable?
A. the manufacturer of a cell phone
B. a person’s gender
C. mileage of a car
D. whether a person is a college graduate
E. whether a person has a charge account
How well a product or a service performs in the marketplace is called the quality of
______________.
A. performance
B. conformance
C. design
D. control
The company financial officer was interested in the average cost of PCs that had been
purchased in the past six months. She took a random sample of the price of 10
computers, with the following results.
$3,250, $1,127, $2,995, $3,250, $3,445, $3,449, $1,482, $6,120, $3,009, $4,000
What is the 10th percentile?
A. $1,304.50
B. $2,617.00
C. $3,415.75
D. $3,587.00
E. $4,212.00
Weighting in exponential smoothing is accomplished by using _____________.
A. first-order autocorrelation
B. smoothing constants
C. the Durbin-Watson method
D. multiplicative decomposing
In order to perform the ________________ , all of the observations in two samples are
combined into a single set and all of the values in the single set are ranked from
smallest to largest.
A. Wilcoxon rank sum test
B. Kruskal-Wallis H test
C. Wilcoxon signed ranks test
D. sign test
An automobile insurance company is in the process of reviewing its policies. The
company is considering increasing the premium charged to drivers under 25. According
to company records, 35 percent of the insured drivers are under the age of 25. Company
records also show that 280 of the 700 insured drivers under the age of 25 have been
involved in at least one automobile accident. On the other hand, only 130 of the 1300
insured drivers 25 years or older have been involved in at least one automobile
accident.
What is the probability that an insured driver of any age will be involved in an
accident?
A. 35%
B. 20.5%
C. 65%
D. 68.3%
E. 79.5%
In testing the difference between two independent population means, if the assumption
is of unequal variances, the critical value of the t statistic is obtained by calculating the
___________________.
A. degrees of freedom
B. sum of the two sample sizes (n1 + n2)
C. p-value
D. pooled variance
The ___________ of two events X and Y is another event that consists of the sample
space outcomes belonging to either event X or event Y or both events X and Y.
A. complement
B. union
C. intersection
D. conditional probability
Suppose that a company’s annual sales were $1,200,000 in 1999. The annual growth
rate of sales from 1999 to 2000 was 16 percent, from 2000 to 2001 it was −5 percent,
and from 2001 to 2002 it was 22 percent.
The geometric mean growth rate of sales over this three-year period is calculated as
10.37 percent. Use the geometric mean growth rate and determine the forecasted sales
for 2004.
A. 1,780,678
B. 1,200,014
C. 1,965,337
D. 1,613,371
E. 1,422,197
In an effort to improve productivity in its factory, a firm recently instituted a training
program for its workers. One of the work crews consisted of 14 workers. Seven workers
from this crew were selected at random to attend the training course. All seven workers
selected successfully completed the training course. The remaining seven workers
served as a control group and did not attend the training course. Three months after the
training course, a foreman who did not know which employees attended the training
course was asked to rank all 14 employees in terms of their productivity. A rank of 14
indicates the most productive employee in the crew, while a rank of 1 indicates the least
productive worker.
Trained Ranks Untrained Ranks
7 6
12 2
14 9
4 3
8 1
13 5
10 11
State the null hypothesis for this problem.
A. H0: DT ≤ DU
B. H0: DT ≥DU
C. H0: DT ≠ DU
D. H0: DT > DU
In the most recent election, 19 percent of all eligible college students voted. If a random
sample of 20 students were surveyed, find the probability that exactly half voted in the
election.
A. .0000
B. .0014
C. .0148
D. .4997
As you probably know, in a given week, the NYSE (New York Stock Exchange) is
generally open from Monday through Friday. If we wanted to use the multiple
regression method with dummy variables to study the impact of the day of the week on
stock market performance, we would need ____ dummy variables.
A. 5
B. 52
C. 4
D. 3
E. 365
Which of the following is not an assumption of the multiple linear regression model?
A. The error terms are independent.
B. The population of error terms has a normal distribution.
C. Populations of error terms observed at different combinations of values of the
independent variable (x1, x2,. . .,xk) have equal variances.
D. The level of measurement of the data for the dependent variable is at least ordinal.
E. At any combination of values of x1, x2, . . . ,xk, the population of potential error term
values has a mean equal to zero.
Consider a Poisson distribution with an average of 3 customers per minute at the local
grocery store. If X = the number of arrivals per minute, find the probability of 3
customers arriving within a minute.
A. 1.00
B. .1494
C. .224
D. .3734
A readability analysis is conducted to determine how easy four different newspapers are
to read for the average citizen. The sample scores are below.
A B C D
50 59 45 62
50 60 48 64
53 63 51 68
58 65 54 70
59 67 55 72
At the α = .01 level of significance, test the claim that the four newspapers have the
same readability level.
A. Reject the null hypothesis.
B. Do not reject the null hypothesis.
In a statistics class, the following 10 scores were randomly selected: 74, 73, 77, 77, 71,
68, 65, 77, 67, 66.
What is the mean?
A. 71.5
B. 72.0
C. 77.0
D. 71.0
E. 73.0
The J.O. Supplies Company buys calculators from a non-US supplier. The probability
of a defective calculator is 10 percent. If 3 calculators are selected at random, what is
the probability that one of the calculators will be defective?
A. .0702
B. .0010
C. .2430
D. .7290
A set of final examination grades in a calculus course was found to be normally
distributed with a mean of 69 and a standard deviation of 9. What proportion of students
scored between 81 and 89?
A. .0668
B. .0132
C. .0786
D. .0529
Find P( < 35) if μ = 40, σx = 16, n = 16.
A. .9944
B. .4483
C. .5517
D. .1056
Employees of a local university have been classified according to gender and job type.
If an employee is selected at random, what is the probability that the employee is
female, given that the employee is a salaried member of the staff?
A. .167
B. .500
C. .625
D. 267
E. .375
In a manufacturing process, if the limits for a control chart are set too _____________,
the risk of not investigating a special cause of variation and possibly not taking a
corrective action ____________.
A. tight, increases
B. loose, increases
C. loose, decreases
D. None of the other choices is correct.
In a local ice skating contest, there were 2 judges and 15 contestants. Each judge was
asked to rate each contestant on a 7-point scale. The most successful candidates
received a rating value of 7, while the least successful candidates received a rating
value of 1. It appears that the bivariate normal probability distribution assumption was
severely violated. The City Council wants to know whether the judges have similar
opinions in rating ice skating competitors. At a significance level of .01, the rejection
point condition for the hypothesis test is
A. reject H0 if rs > .457.
B. reject H0 if rs > .623.
C. reject H0 if rs > .441.
D. reject H0 if rs > .646.
E. reject H0 if rs > .689.
Historical data for a local manufacturing company show that the average number of
defects per product produced is 2. In addition, the number of defects per unit is
distributed according to a Poisson distribution. A batch has just been completed. What
is the probability that the first three units manufactured in this batch will contain at least
a total of 4 defects?
A. .8488
B. .7149
C. .1512
D. .2851
Suppose that and R charts based on subgroups of size 4 are being used to monitor the
tire diameter of a new radial tire. The and R charts are found to be in statistical control
with = 50.25, = 8. inches. A histogram of the tire diameter measurements indicates
that these measurements are approximately normally distributed. If the tire diameter
specifications are 50 inches 1 inch, is the process capable of meeting the specifications?
A. Yes
B. No
A test of driving ability is given to a random sample of 10 student drivers before and
after they complete a formal driver education course. Results follow.
Calculate the t statistic to test that there is no difference between the before-class scores
and the after-class scores.
Complete the following partial ANOVA table from a simple linear regression analysis
with a sample size of 16 observations. Find the F statistic to test the significance of the
model.
Consider the following partial analysis of variance table from a randomized block
design with 6 blocks and 4 treatments.
Source Sum of Squares
Treatments 15.93
Blocks 42.09
Error 23.84
Total 81.86
Determine the degrees of freedom for error.
A local tire dealer wants to predict the number of tires sold each month. He believes
that the number of tires sold is a linear function of the amount of money invested in
advertising. He randomly selects 6 months of data consisting of tire sales (in thousands
of tires) and advertising expenditures (in thousands of dollars). Based on the data set
with 6 observations, the simple linear regression equation of the least squares line is ŷ =
3 + 1x.
MSE = 4
Use the least squares regression equation and estimate the monthly tire sales when
advertising expenditures = $4,000.
Consider the following set of quarterly sales data given in thousands of dollars.
Write an appropriate dummy variable model that incorporates a linear trend and
constant seasonal variation.
A local grocery market is studying whether to offer a loyalty program to its customers.
In its final analyses the following groups are being used to categorize loyalty card
customers: family income and number of children. Using the classification tree below,
estimate the percentage of customers with an income of $50,000 with 2 children who
would use a loyalty card
Suppose that a realtor is interested in comparing the price of midrange homes in two
cities in a midwestern state. She conducts a small survey in the two cities, looking at the
price of midrange homes. Assume equal population variances.
Calculate the 95 percent confidence interval.
Consider the following partial computer output from a simple linear regression analysis.
Write the equation of the least squares line.
Suppose you randomly select 3 DVDs from a production run of 10. Of the 10 DVDs, 9
are expected to last a minimum of 3 years. What is the standard deviation of the random
variable x?
Wax-com Electronics Inc. claims that a certain circuit board has a median operating life
of less than 20,000 hours. A random sample of 25 such circuit boards showed 8 circuit
boards failing before 20,000 hours and 17 circuit boards failing after 20,000 hours.
Assume the useful life of the circuit board is not normally distributed. At α = .05, can it
be concluded that the sample contradicts the company’s claim? Assume the useful life
of the circuit board is not normally distributed.
A. Reject the null hypothesis.
B. Do not reject the null hypothesis.
Consider the following partial computer output from a simple linear regression analysis.
What is the unexplained variance?
A manufacturing company produces part QV2Y for the aerospace industry. This
particular part can be manufactured using 3 different production processes. The
management wants to know if the quality of the units of part QV2Y is the same for all
three processes. The production supervisor obtained the following data: Process 1 had
29 defective units in 240 items, Process 2 produced 12 defective units in 180 items, and
Process 3 manufactured 9 defective units in 150 items. At a significance level of .05,
the management wants to perform a hypothesis test to determine whether the quality of
items produced appears to be independent of the production process used. Calculate the
expected number of defective units produced by Process 1.
A worldwide personal products manufacturer is working on a new hair care product. In
the past, 85 percent of new hair care products introduced by this company have become
successful (15 percent have failed). Obviously, the marketing research department plays
a large role in the introduction of any new product. Historically, 85 percent of the
successful products have a favorable rating from marketing research studies and 20
percent of the unsuccessful products have favorable ratings. For the new hair care
product, the marketing unit has issued a favorable rating. What is the probability that
the new product will be successful?