Which of the following statements about causes of variation are TRUE?
I. Assignable variation is random in nature and cannot be eliminated or reduced.
II. Chance variation cannot be completely eliminated unless there are significant
methods, techniques, or equipment used in the process.
III. Chance variation usually cannot be corrected, while assignable variation is
correctable.
A. I only
B. II only
C. II and III
D. I and III
The tread life of tires mounted on light-duty trucks follows the normal probability
distribution with a mean of 60,000 miles and a standard deviation of 4,000 miles.
Suppose we select a sample of 40 tires and use a simulator to determine the tread life.
What is the likelihood of finding that the sample mean is between 59,050 and 60,950?
A. 0.4332
B. 0.8664
C. 1.00
D. Very likely
When testing the difference between two population means, the sample variances are
pooled to estimate the population variance when ________________.
A. The population variances are known and equal
B. The population means are known
C. The population variances are assumed unequal and unknown
D. The population variances are assumed equal but unknown
Consider two populations with the same mean. Since they have the same mean, then:
A. Their standard deviations must also be the same.
B. Their medians must also be the same.
C. Their modes must also be the same.
D. None of these is correct.
Refer to the following information from a frequency distribution for “heights of college
women” recorded to the nearest inch: the first two class midpoints are 62.5″ and 65.5″.
What are the class limits for the third class?
A. 64 and up to 67
B. 67 and 69
C. 67 and up to 70
D. 66 and 68
When is it appropriate to use the paired difference t-test?
A. When four samples are compared at once
B. When any two samples are compared
C. When two independent samples are compared
D. When two dependent samples are compared
Which of the following is correct about a probability distribution?
A. The sum of all possible outcomes must equal 1.0.
B. The outcomes must be mutually exclusive.
C. The probability of each outcome must be between 0.0 and 1.0 inclusive.
D. All apply.
A recent study of the relationship between social activity and education for a sample of
corporate executives showed the following results.
The appropriate test statistic for the analysis is a(n) __________.
A. F-statistic
B. t-statistic
C. Chi-square statistic
D. z-statistic
Sweetwater & Associates write weekend trip insurance at a very nominal charge.
Records show that the probability that a motorist will have an accident during the
weekend and file a claim is 0.0005. Suppose they wrote 400 policies for the coming
weekend, what is the probability that exactly two claims will be filed?
A. 0.8187
B. 0.2500
C. 0.0164
D. 0.0001
Two accounting professors decided to compare the variance of their grading procedures.
To accomplish this, they each graded the same 10 exams, with the following results:
What are the degrees of freedom for the numerator of the F ratio?
A. 8
B. 9
C. 10
D. 18
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 assumptions do you need to make about the shape
of the population distribution of all possible tax preparation times to make inferences
about the mean time to complete a tax form?
A. The population distribution is skewed to the right.
B. The population distribution is skewed to the left.
C. The population distribution is normal.
D. The shape of the population distribution does not matter.
The following is a Poisson probability distribution with = 0.1.
The variance of the distribution is ______.
A. 1.0
B. 0.9046
C. 3.0
D. 0.1
The time to fly between New York City and Chicago is uniformly distributed with a
minimum of 120 minutes and a maximum of 150 minutes. What is the distribution’s
standard deviation?
A. 8.66 minutes
B. 75 minutes
C. 135 minutes
D. 270 minutes
If two events are mutually exclusive, then P(A and B) = P(A)P(B).
Data for selected vegetables purchased at wholesale prices for 1995 and 2007 are
shown next.
What is the Laspeyres price index?
A. 98.4
B. 107.0
C. 108.0
D. 117.5
If the upper and lower control limits are set at 3 standard deviations from the mean, we
would expect that:
A. 99.7% of the sample means are within the control limits.
B. 95% of the sample means are within the control limits.
C. about 68% of the sample means are within the control limits.
D. about 5% of the sample means are outside the control limits.
David’s gasoline station offers 4 cents off per gallon if the customer pays in cash and
does not use a credit card. Past evidence indicates that 40% of all customers pay in
cash. During a one-hour period, 15 customers buy gasoline at this station. This situation
is an example of what type of discrete probability distribution?
A. Continuous probability distribution
B. Poisson probability distribution
C. Binomial probability distribution
D. Hypergeometric probability distribution
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 ANOVA shows the following results:
What is the value of the standard error of estimate?
A. 9.310
B. 8.778
C. 8.328
D. 86.68
A new machine used in the production of motor mount bolts was put into operation.
Five samples of size 100 were randomly selected and the number of defectives in each
sample was noted.
The measurement of quality is based on:
A. an attribute.
B. a variable.
C. a scale.
D. a chart.
What is the relationship between the variance and the standard deviation?
A. Variance is the square root of the standard deviation.
B. Variance is the square of the standard deviation.
C. Variance is twice the standard deviation.
D. There is no constant relationship between the variance and the standard deviation.
Data for selected fruits purchased at wholesale prices for 2005 and 2009 are shown
next.
What is your interpretation of the Laspeyres price index?
A. Value rose 9.4%.
B. Value rose 79.1%.
C. Value rose 12.7%.
D. Value rose 12.0%.
Which of the following are the same between a confidence interval and a prediction
interval?
A. The formulas are the same.
B. They both use the standard error of estimate.
C. They both provide a confidence interval for the mean.
D. A confidence interval and prediction interval are the same width.
A hypothesis test is conducted at the .05 level of significance to test whether or not the
population correlation is zero. If the sample consists of 25 observations and the
correlation coefficient is 0.60, what is the computed value of the test statistic? Round to
two decimal places.
A. 1.96
B. 2.07
C. 2.94
D. 3.60
A company is studying the number of monthly absences among its 125 employees. The
following probability distribution shows the likelihood that people were absent 0, 1, 2,
3, 4, or 5 days last month.
What is the standard deviation of the number of days absent?
A. 1.1616
B. 0
C. 1.6595
D. 1.0778
In a departmental review of employee performance, three employees were scored a 4
(excellent performance), five employees were scored a 3 (average performance), and
one employee was scored a 1 (below average performance). To compute a weighted
mean, the weights would be ___________________.
A company set up a kiosk in the Mall of America for several hours and asked randomly
selected people which color cell phone cover was their favorite. The results follow:
What is the probability that red is the favorite color, given that the person’s age is 21 or
older?
When the population standard deviations are equal but unknown, a test for the
differences between two populations assumes that the populations are _____________
distributed.
What are the five assumptions of linear multiple regression?
For a frequency distribution of quantitative data, if every individual, object, or
measurement can be assigned to a class, the frequency distribution is __________.
You have a decision to invest $10,000 in any of four different companies. You estimate
the probabilities that the economy will be favorable or unfavorable, and you estimate
the percent returns over the next year.
What is the expected value for Company 3?
The lowest level of measurement for a chi-square goodness-of-fit test is the
______________ level.
A multiple regression analysis showed the following ANOVA table result.
Based on the information in the ANOVA, how many independent variables were
included in the multiple regression analysis?
A local grocery store wants to estimate the mean daily number of gallons of milk sold
to customers. Assume the number of gallons sold follows the normal distribution, with a
population standard deviation of 5.10 gallons. A random sample of 60 days shows that
the mean daily number of gallons sold is 10.00. Compute a 99% confidence interval for
the population mean.