When testing a hypothesis about a single mean, if the sample size is 20, the population
standard deviation is unknown, and the population is assumed to be a normal
distribution, the correct test statistic to use is ___________.
A. r
B. z
C. t
D. p-value
The EPA has stipulated that the Pollution Standard Index (PSI) for clean air standards is
to average no more than 100. A random sample of 9 days for the city of Acme showed
PSI readings of 144, 85, 90, 120, 150, 105, 93, 130, and 115.Assume the population of
PSI readings is highly nonnormal. The EPA wants to determine if there is significant
evidence to conclude that Acme air is dirtier than the stipulated clean air standards. The
test is conducted at α = .05 and the p value is found to be .254. Based on this result,
provide a one-sentence managerial conclusion.
A. Acme air is dirtier than the EPA stipulated clean air standards.
B. We cannot conclude that Acme air is dirtier than the EPA stipulated clean air
standards.
C. Acme air is better than the EPA stipulated clean air standards.
D. Acme air meets the EPA stipulated clean air standards.
____________ values of the standard deviation result in a normal curve that is wider
and flatter.
A. Smaller
B. Equal
C. Larger
D. Uniform
How well a product or service performs in the marketplace is called
A. process capability.
B. quality of conformance.
C. quality of performance.
D. quality of design.
E. process control.
One die is thrown. What is the expected value of the number of dots on the top face of
the die?
A. 1.0
B. 3.5
C. 4.0
D. 3.0
In general, the number of dummy variables used to model constant seasonal variation is
equal to the number of
A. seasons.
B. seasons minus 1.
C. seasons plus 1.
D. seasons minus 2.
E. seasons divided by two.
An aptitude test has a mean score of 80 and a standard deviation of 5. The population of
scores is normally distributed. What proportion of tests has scores over 90?
A. .9772
B. .0228
C. .9544
D. .0456
Quality control is an important issue at ACME Company, which manufactures light
bulbs. Totest the life-hours of their light bulbs, they randomly sampled nine light bulbs
and measured how many hours they lasted: 378, 361, 350, 375, 200, 391, 375, 368, 321.
What is the mode?
A. 375
B. 368
C. 389.9
D. 200
E. 346.6
The ____________ hypothesis will be accepted only if there is convincing sample
evidence that it is true.
A. z test
B. alternative
C. null
D. true
A copy machine service company provides maintenance and repair service for different
types and brands of copiers. The manager of the repair department wants to know if the
repair time for brand A is higher than the repair time for brand B. The manager
randomly selects 8 repair records associated with brand A and 8 repair records
associated with brand B. The distribution of repair times for both brand A and brand B
is highly skewed. Which one of the following nonparametric tests is appropriate for this
problem?
A. Wilcoxon signed ranks test
B. Wilcoxon rank sum test
C. sign test
D. Kruskal-Wallis test
E. Spearman’s rank correlation test
There is little difference between the values of tα/2 and zα/2 when
A. the sample size is small.
B. the sample size is large.
C. the sample mean is small.
D. the sample mean is large.
E. the sample standard deviation is small.
The relationship between the standard normal random variable z and normal random
variable X is that
A. only the normal random variable X is continuous.
B. only the standard normal variable z is continuous.
C. the standard normal variable z counts the number of standard deviations that the
value of the normal random variable X is away from its mean.
D. the values of the standard normal random variable z cannot be negative.
E. the values of the normal random variable X cannot be negative.
Which of the following is a violation of one of the major assumptions of the simple
regression model?
A. The error terms are independent of each other.
B. A histogram of the residuals forms a bell-shaped, symmetrical curve.
C. The error terms show no pattern.
D. As the value of x increases, the value of the error term also increases.
In a simple regression analysis for a given data set, if the null hypothesis β = 0 is
rejected, then the null hypothesis ρ = 0 is also rejected. This statement is ___________
true.
A. always
B. never
C. sometimes
A person’s utility is determined by the preferences he/she exhibits for decision choices
involving __________.
A. certainty
B. uncertainty
C. risk
D. Bayes’ Theorem
In a statistics class, 10 scores were randomly selected with the following results (mean
= 71.5): 74, 73, 77, 77, 71, 68, 65, 77, 67, 66.
What is the range?
A. 22.72
B. 12.00
C. 4.77
D. 516.20
E. 144.00
In utility theory, a(n)__________________ decision maker is an individual who will
choose the decision alternative having the highest expected profit.
A. high-risk
B. low-risk
C. risk-neutral
D. posterior
The mean of a hypergeometric random variable is defined as
A. n (r/N).
B. N (r/n).
C. npq.
D. np.
Researchers studied the role that the age of workers has in determining the hours per
month spent on personal tasks. A sample of 1,686 adults were observed for one month.
The data follow.
Construct an 88 percent confidence interval for the mean hours spent on personal tasks
for 18- to 24-year-olds.
A. [4.09, 4.25]
B. [4.11, 4.23]
C. [4.08, 4.26]
D. [4.14, 4.20]
E. [4.15, 4.19]
In a simple linear regression model, the slope term is the change in the mean value of y
associated with _____________ in x.
A. a corresponding increase
B. a variable change
C. no change
D. a one-unit increase
A multiple-choice test has 30 questions and each one has five possible answers, of
which only one is correct. If all answers were guesses, find the probability of getting
exactly four correct answers.
A. .0604
B. .1325
C. .2552
D. .8000
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. When ranking the dealers, how many outcomes are possible?
A. 6
B. 9
C. 8
D. 10
E. 12
A manufacturer of personal computers tests competing brands and finds that the amount
of energy they require is normally distributed with a mean of 285 kwh and a standard
deviation of 9.1 kwh. If the lowest 25 percent and the highest 30 percent are not
included in a second round of tests, what are the upper and lower limits for the energy
amounts of the remaining computers?
A. [269.76, 300.24]
B. [278.86, 289.78]
C. [280.22, 289.78]
D. [280.22, 300.24]
The ____________________ is the proportion of the total variation in the dependent
variable explained by the regression model.
A. coefficient of determination
B. correlation coefficient
C. slope
D. standard error
What is the probability that an even number appears on the toss of a die?
A. 0.5
B. 0.33
C. 0.25
D. 0.67
E. 1.00
In a manufacturing process, a machine produces bolts that have an average length of 3
inches with a variance of .03. If we randomly select three bolts from this process, what
is the standard deviation of the sampling distribution of the sample mean?
A. .03
B. .01
C. .1732
D. .0577
E. .10
A machine is made up of 3 components: an upper part, a middle part, and a lower part.
The machine is then assembled. 5 percent of the upper parts are defective, 4 percent of
the middle parts are defective, and 1 percent of the lower parts are defective. What is
the probability that a machine is not defective?
A. 0.1000
B. 0.9029
C. 0.8000
D. 0.0002
E. 0.7209
The ___________ is a graphic that is used to check visually whether data come from a
normal population.
A. exponential plot
B. normal probability plot
C. box-and-whiskers plot
D. normal distribution graph
The _____________________ is the difference between the expected value of sampling
and the cost of sampling.
A. expected monetary value
B. expected value of perfect information
C. expected value of sample information
D. expected net gain of sampling
In a statistics class, 10 scores were randomly selected, with the following results:
74, 73, 77, 77, 71, 68, 65, 77, 67, 66.
What is the 10th percentile?
A. 65.5
B. 67.3
C. 66.75
D. 73.85
E. 77.0
_____________ values of the standard deviation result in a normal curve that is
narrower and
more peaked.
A. Smaller
B. Equal
C. Larger
D. Uniform
When a confidence interval for a population proportion is constructed for a sample size
n = 30 and the value of = .4, the interval is based on
A. the z distribution.
B. the t distribution.
C. the exponential distribution.
D. the Poisson distribution.
E. None of the other choices is correct.
A quantity that measures the variation of a population or a sample relative to its mean is
called the ____________.
A. range
B. standard deviation
C. coefficient of variation
D. variance
E. interquartile range
The EPA has stipulated that the Pollution Standard Index (PSI) for clean air standards is
to average no more than 100. A random sample of 9 days for the city of Acme showed
PSI readings of 144, 85, 90, 120, 150, 105, 93, 130, and 115. Assume the population of
PSI readings is highly nonnormal. Is there significant evidence to conclude that Acme
air is dirtier than the stipulated clean air standards?
A. Reject the null hypothesis.
B. Do not reject the null hypothesis.
The AAA Co. is interested in the level of satisfaction of their employees with the
benefit package that they offer compared to their major competitors. A consultant hired
to conduct the satisfaction survey told AAA Co. that the distribution of level of
satisfaction at other companies is displayed below.
Very Satisfied 5%
Satisfied 30%
Neutral 20%
Dissatisfied 40%
Very Dissatisfied 5%
A survey of 125 AAA employees gave the following results.
Very Satisfied 15
Satisfied 52
Neutral 20
Dissatisfied 30
Very Dissatisfied 8
Total 125
What are the degrees of freedom for testing the goodness of fit at α = .05?
An investor is looking at three possible investments: growth stock, blue chip stock, or
municipal bonds. The investment performance will vary depending on the investment
market condition of bull (market rising), flat, or bear (market falling). The investment
return for each investment for the corresponding market conditions is given below.
Which investment would the investor select if using the maximax criterion?
The price and quantity of several food items are listed below for the years 1990 and
2000.
Compute the Paasche index, using 1990 as the base year.
The quality control manager for NKA Inc. must decide whether to accept (alternative
1), further analyze (alternative 2), or reject (alternative 3) an incoming shipment (lot) of
microchips. The historical data indicate that there is a 30 percent chance that the lot is
poor quality (S1), 50 percent chance that the lot is fair quality (S2), and 20 percent
chance that the lot is good quality (S3). Assume the following payoff table is available.
The values in the payoff table are in thousands of dollars.
What alternative action should be selected according to the maximin criterion?
Block
Treatment 1 2 3 4 Treatment Mean
Tr1 2 1 2 3 2
Tr2 4 4 1 1 2.5
Tr3 3 4 3 2 3
Block Mean 2 3 3 2 overall mean = 2.5
Consider the randomized block design with 4 blocks and 3 treatments given above.
What are the degrees of freedom for treatments?
A data set with 7 observations yielded the following. Use the simple linear regression
model.
Calculate the correlation coefficient.
The coffee and soup machine at the local subway station is supposed to fill cups with 6
ounces of soup. Ten cups of soup are bought, with results of a mean of 5.93 ounces and
a standard deviation of 0.13 ounces. Construct a 95.44 percent tolerance interval of the
machine-fill amounts and a 95 percent confidence interval for the true machine-fill
amount.
Find a 95 percent confidence interval for the difference between the proportions of
people who prefer cola versus root beer (RB), where cola = .21, RB = .12, ncola =
200, and nRB = 150.
It has been hypothesized that on average employees spend one hour a day playing video
games at work. To test this at her company, a manager takes a random sample of 35
employees, who showed a mean time of 55 minutes per day with an assumed
population standard deviation of 5 minutes. Calculate a confidence interval to test the
hypotheses that the employees spend a different amount of time from one hour (60
minutes) at α = .02 and interpret.
Suppose you are a researcher investigating the annual sales differences among five
categories of businesses. The study looks at 55 companies equally divided among
categories A, B, C, D, and E.
Complete the following ANOVA table and determine the value of the F statistic.
Source SS DF MS F
Treatment 583.39
Error
Total 1555.57
Find a Tukey simultaneous 95 percent confidence interval for μ1 − μ2, where 1 =
33.98, 2 = 36.56, and MSE = 0.669. There were 15 observations total and 3
treatments. Assume that the number of observations in each treatment is equal.
In a sample of n = 16 selected from a normally distributed population, we find a
population standard deviation of s = 10. What is the value of χ2 if we are testing H0: σ2
= 144?