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TABLE 8-7
A hotel chain wants to estimate the mean number of rooms rented daily in a given
month. The population of rooms rented daily is assumed to be normally distributed for
each month with a standard deviation of 240 rooms. During February, a sample of 25
days has a sample mean of 370 rooms.
True or False: Referring to Table 8-7, the parameter of interest is the proportion of the
rooms rented daily in a given month.
True or False: Managers need an understanding of statistics to be able to present and
describe information accurately, draw conclusions about large populations based on
small samples, improve processes, and make reliable forecasts.
True or False: The coefficient of variation is expressed as a percentage.
TABLE 8-8
The president of a university would like to estimate the proportion of the student
population that owns a personal computer. In a sample of 500 students, 417 own a
personal computer.
True or False: Referring to Table 8-8, we are 99% confident that between 79.11% and
87.69% of the student population own a personal computer.
True or False: The coefficient of variation is a measure of relative variation.
TABLE 8-9
A university wanted to find out the percentage of students who felt comfortable
reporting cheating by their fellow students. A survey of 2,800 students was conducted
and the students were asked if they felt comfortable reporting cheating by their fellow
students. The results were 1,344 answered "Yes" and 1,456 answered "No."
True or False: Referring to Table 8-9, a 99% confidence interval will contain 99% of the
student population who feel comfortable reporting cheating by their fellow students.
True or False: The expected return of a two-asset portfolio is equal to the product of the
weight assigned to the first asset and the expected return of the first asset plus the
product of the weight assigned to the second asset and the expected return of the second
asset.
True or False: The relative frequency is the frequency in each class divided by the total
number of observations.
TABLE 12-6
According to an article in Marketing News, fewer checks are being written at the
grocery store checkout than in the past. To determine whether there is a difference in
the proportion of shoppers who pay by check among three consecutive years at a 0.05
level of significance, the results of a survey of 500 shoppers in three consecutive years
are obtained and presented below.
True or False: Referring to Table 12-6, there is insufficient evidence to conclude that the
proportions between year 1 and year 3 are different at a 0.05 level of significance.
True or False: In a hypothesis test, it is irrelevant whether the test is a one-tail or
two-tail test.
True or False: Referring to Table 14-17, the null hypothesis should be
rejected at a 10% level of signi!cance when testing whether there is
a signi!cant relationship between the number of weeks a worker is
unemployed due to a layo% and the entire set of explanatory
variables.
TABLE 14-17
Given below are results from the regression analysis where the
dependent variable is the number of weeks a worker is unemployed
due to a layo% (Unemploy) and the independent variables are the age
of the worker (Age) and a dummy variable for management position
(Manager: 1 = yes, 0 = no).
The results of the regression analysis are given below:
For some value of Z, the value of the cumulative standardized normal distribution is
0.8340. The value of Z is
A) 0.07.
B) 0.37.
C) 0.97.
D) 1.06.
Which of the following yields a systematic sample?
A) All students in a class are divided into groups of 15. One student is randomly chosen
from the 1st group, the remaining observations are every 15th student thereafter.
B) The best 15 students, according to the opinion of the instructor, in a class are
selected.
C) All students in a class are grouped according to their gender. A random sample of 8
is selected from the males and a separate random sample of 7 is drawn from the
females.
D) A random sample of 15 students is selected from a class without replacement.
TABLE 17-1
A real estate builder wishes to determine how house size (House) is influenced by
family income (Income), family size (Size), and education of the head of household
(School). House size is measured in hundreds of square feet, income is measured in
thousands of dollars, and education is in years. The builder randomly selected 50
families and ran the multiple regression. Microsoft Excel output is provided below:
Referring to Table 17-1, what is the predicted house size (in hundreds of square feet) for
an individual earning an annual income of $40,000, having a family size of 4, and going
to school a total of 13 years?
A) 11.43
B) 15.15
C) 24.88
D) 53.87
TABLE 4-4
Suppose that patrons of a restaurant were asked whether they preferred water or
whether they preferred soda. 70% said that they preferred water. 60% of the patrons
were male. 80% of the males preferred water.
Referring to Table 4-4, the probability that a randomly selected patron is a female is
________.
After estimating a trend model for annual time-series data, you obtain the following
residual plot against time.
The problem with your model is that
A) the cyclical component has not been accounted for.
B) the seasonal component has not been accounted for.
C) the trend component has not been accounted for.
D) the irregular component has not been accounted for.
TABLE 9-8
One of the biggest issues facing e-retailers is the ability to turn browsers into buyers.
This is measured by the conversion rate, the percentage of browsers who buy something
in their visit to a site. The conversion rate for a company's website was 10.1%. The
website at the company was redesigned in an attempt to increase its conversion rates. A
sample of 200 browsers at the redesigned site was selected. Suppose that 24 browsers
made a purchase. The company officials would like to know if there is evidence of an
increase in conversion rate at the 5% level of significance.
Referring to Table 9-8, the null hypothesis will be rejected if the test statistic is
A) greater than 1.645.
B) less than 1.645.
C) greater than -1.645.
D) less than -1.645.
TABLE 11-1
An airline wants to select a computer software package for its reservation system. Four
software packages (1, 2, 3, and 4) are commercially available. The airline will choose
the package that bumps as few passengers as possible during a month. An experiment is
set up in which each package is used to make reservations for 5 randomly selected
weeks. (A total of 20 weeks was included in the experiment.) The number of passengers
bumped each week is obtained, which gives rise to the following Excel output:
ANOVA
Referring to Table 11-1, the among-group (between-group) mean squares is
A) 8.525.
B) 70.8.
C) 212.4.
D) 637.2.
A confidence interval was used to estimate the proportion of statistics students who are
females. A random sample of 72 statistics students generated the following 90%
confidence interval: (0.438, 0.642). Based on the interval above, is the population
proportion of females equal to 0.60?
A) No, and we are 90% sure of it.
B) No. The proportion is 54.17%.
C) Maybe. 0.60 is a believable value of the population proportion based on the
information above.
D) Yes, and we are 90% sure of it.
TABLE 4-4
Suppose that patrons of a restaurant were asked whether they preferred water or
whether they preferred soda. 70% said that they preferred water. 60% of the patrons
were male. 80% of the males preferred water.
Referring to Table 4-4, the probability that a randomly selected patron prefers soda is
________.
TABLE 17-4
You decide to predict gasoline prices in different cities and towns in the United States
for your term project. Your dependent variable is price of gasoline per gallon and your
explanatory variables are per capita income, the number of firms that manufacture
automobile parts in and around the city, the number of new business starts in the last
year, population density of the city, percentage of local taxes on gasoline, and the
number of people using public transportation. You collected data of 32 cities and
obtained a regression sum of squares SSR= 122.8821. Your computed value of standard
error of the estimate is 1.9549.
Referring to Table 17-4, what is the value of the coefficient of multiple determination?
A) 0.2225
B) 0.4576
C) 0.5626
D) 0.6472
Which of the following about the binomial distribution is not a true statement?
A) The probability of the event of interest must be constant from trial to trial.
B) Each outcome is independent of the other.
C) Each outcome may be classified as either "event of interest" or "not event of
interest."
D) The variable of interest is continuous.
When using the exponentially weighted moving average for purposes of forecasting
rather than smoothing,
A) the previous smoothed value becomes the forecast.
B) the current smoothed value becomes the forecast.
C) the next smoothed value becomes the forecast.
D) None of the above.
TABLE 19-4
A stock portfolio has the following returns under the market conditions listed below.
Referring to Table 19-4, what is the return to risk ratio?
A) 0.64
B) 1.08
C) 1.18
D) 2.00
TABLE 17-10
Given below are results from the regression analysis where the dependent variable is
the number of weeks a worker is unemployed due to a layoff (Unemploy) and the
independent variables are the age of the worker (Age), the number of years of education
received (Edu), the number of years at the previous job (Job Yr), a dummy variable for
marital status (Married: 1 = married, 0 = otherwise), a dummy variable for head of
household (Head: 1 = yes, 0 = no) and a dummy variable for management position
(Manager: 1 = yes, 0 = no). We shall call this Model 1. The coefficient of partial
determination ( ) of each of the 6 predictors are, respectively,
0.2807, 0.0386, 0.0317, 0.0141, 0.0958, and 0.1201.
Model 2 is the regression analysis where the dependent variable is Unemploy and the
independent variables are Age and Manager. The results of the regression analysis are
given below:
Referring to Table 17-10, Model 1, which of the following is a correct statement?
A) 40.30% of the total variation in the number of weeks a worker is unemployed due to
a layoff can be explained by the age of the worker, the number of years of education
received, the number of years at the previous job, marital status, whether the worker is
the head of household and whether the worker is a manager.
B) 40.30% of the total variation in the number of weeks a worker is unemployed due to
a layoff can be explained by the age of the worker, the number of years of education
received, the number of years at the previous job, marital status, whether the worker is
the head of household and whether the worker is a manager after adjusting for the
number of predictors and sample size.
C) 40.30% of the total variation in the number of weeks a worker is unemployed due to
a layoff can be explained by the age of the worker, the number of years of education
received, the number of years at the previous job, marital status, whether the worker is
the head of household and whether the worker is a manager after adjusting for the level
of significance.
D) 40.30% of the total variation in the number of weeks a worker is unemployed due to
a layoff can be explained by the age of the worker, the number of years of education
received, the number of years at the previous job, marital status, whether the worker is
the head of household and whether the worker is a manager holding constant the effect
of all the independent variables.
TABLE 12-10
One criterion used to evaluate employees in the assembly section of a large factory is
the number of defective pieces per 1,000 parts produced. The quality control
department wants to find out whether there is a relationship between years of
experience and defect rate. Since the job is repetitious, after the initial training period
any improvement due to a learning effect might be offset by a loss of motivation. A
defect rate is calculated for each worker in a yearly evaluation. The results for 100
workers are given in the table below.
Referring to Table 12-10, for the cell with 1 to 4 years of training time and a high defect
rate, what is the contribution to the overall X2 statistic for the independence test?
A) 0.36
B) 0.1296
C) 0.015
D) 0.0144
TABLE 17-8
The superintendent of a school district wanted to predict the percentage of students
passing a sixth-grade proficiency test. She obtained the data on percentage of students
passing the proficiency test (% Passing), daily mean of the percentage of students
attending class (% Attendance), mean teacher salary in dollars (Salaries), and
instructional spending per pupil in dollars (Spending) of 47 schools in the state.
Following is the multiple regression output with Y = % Passing as the dependent
variable, X1 = % Attendance, X2 = Salaries and X3 = Spending:
Referring to Table 17-8, which of the following is the correct null hypothesis to test
whether instructional spending per pupil has any effect on the percentage of students
passing the proficiency test, taking into account the effect of all the other independent
variables?
A) H0 : β0 = 0
B) H0 : β1 = 0
C) H0 : β2 = 0
D) H0 : β3 = 0
TABLE 15-3
A chemist employed by a pharmaceutical firm has developed a muscle relaxant. She
took a sample of 14 people suffering from extreme muscle constriction. She gave each a
vial containing a dose (X) of the drug and recorded the time to relief (Y) measured in
seconds for each. She fit a curvilinear model to this data. The results obtained by
Microsoft Excel follow
Referring to Table 15-3, suppose the chemist decides to use an F test to determine if
there is a significant curvilinear relationship between time and dose. The p-value of the
test is ________.
TABLE 3-3
The ordered array below represents the number of vitamin supplements sold by a health
food store in a sample of 16 days.
19, 19, 20, 20, 22, 23, 25, 26, 27, 30, 33, 34, 35, 36, 38, 41
Note: For this sample, the sum of the values is 448, and the sum of the squared
differences between each value and the mean is 812.
Referring to Table 3-3, the kurtosis statistic of the number of vitamin supplements sold
in this sample is ________.
TABLE 5-11
Subscribers to Investment Advice White Letters perform security transactions at the rate
of five trades per month. Assume that one of the subscribers performs transactions at
this rate and the probability of a transaction for any two months is the same and the
number of transactions in one month is independent of the number of transactions in
another month.
Referring to Table 5-11, what is the probability that fewer than two security transactions
will be conducted in one month?
TABLE 5-10
An accounting firm in a college town usually recruits employees from two of the
universities in town. This year, there are fifteen graduates from University A and five
from University B and the firm decides to hire six new employees from the two
universities.
Referring to Table 5-10, what is the probability that two of the new employees will be
from University A?
TABLE 18-8
Recently, a university switched to a new type of computer-based registration. The
registrar is concerned with the amount of time students are spending on the computer
registering under the new system. She decides to randomly select 8 students on each of
the 12 days of the registration and determine the time each spends on the computer
registering. The range, mean, and standard deviation of the times required to register are
in the table that follows.
Referring to Table 18-8, an R chart is to be constructed for the time required to register.
The center line of this R chart is located at ________.
TABLE 17-10
Given below are results from the regression analysis where the dependent variable is
the number of weeks a worker is unemployed due to a layoff (Unemploy) and the
independent variables are the age of the worker (Age), the number of years of education
received (Edu), the number of years at the previous job (Job Yr), a dummy variable for
marital status (Married: 1 = married, 0 = otherwise), a dummy variable for head of
household (Head: 1 = yes, 0 = no) and a dummy variable for management position
(Manager: 1 = yes, 0 = no). We shall call this Model 1. The coefficient of partial
determination ( ) of each of the 6 predictors are, respectively,
0.2807, 0.0386, 0.0317, 0.0141, 0.0958, and 0.1201.
Model 2 is the regression analysis where the dependent variable is Unemploy and the
independent variables are Age and Manager. The results of the regression analysis are
given below:
Referring to Table 17-10, Model 1, what is the standard error of estimate?
TABLE 3-4
The ordered array below represents the number of cargo manifests approved by customs
inspectors of the Port of New York in a sample of 35 days:
16, 17, 18, 18, 19, 20, 20, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23, 24, 24, 24, 25, 25,
26, 26, 26, 27, 28, 28, 29, 29, 31, 31, 32, 32
Note: For this sample, the sum of the values is 838, and the sum of the squared
differences between each value and the mean is 619.89.
Referring to Table 3-4, construct a boxplot of this sample.
TABLE 12-7
Data on the percentage of 200 hotels in each of the three large cities across the world on
whether minibar charges are correctly posted at checkout are given below.
At the 0.05 level of significance, you want to know if there is evidence of a difference
in the proportion of hotels that correctly post minibar charges among the three cities.
Referring to Table 12-7, what are the values of the absolute difference and the critical
range for the Marascuilo procedure to test for the difference in proportions between
Hong Kong and Paris using a 0.05 level of significance?
TABLE 6-7
A company has 125 personal computers. The probability that any one of them will
require repair on a given day is 0.15.
Referring to Table 6-7 and assuming that the number of computers that requires repair
on a given day follows a binomial distribution, compute the probability that there will
be exactly 10 computers that require repair on a given day using a normal
approximation.
