A researcher wants to conduct a before/after study on 11 subjects to determine if a new
cholesterol medication results in higher HDL cholesterol readings. The null hypothesis
is that the average difference is zero while the alternative hypothesis is that the average
difference is not zero. Scores are obtained on the subjects both before and after taking
the medication. After subtracting the after scores from the before scores, the average
difference is computed to be “2.40 with a sample standard deviation of 1.21. A 0.05
level of significance is selected. Assume that the differences are normally distributed in
the population. The table tvalue for this test is _______.
a) 1.812
b) 2.228
c) 2.086
d) 2.262
e) 3.2467
A researcher is estimating the average difference between two population means based
on matched”pairs samples. She gathers data on each pair in the study resulting in:
Assume that the data are normally distributed in the population. A 95% confidence
interval would be _______.
a) -3.02 to -0.18
b) -1.6 to -1.09
c) -2.11 to 1.09
d) -2.11 to -1.09
e) -3.23 to 2.23
Which of the following is not a component of time series data?
a) Trend
b) Seasonal fluctuations
c) Cyclical fluctuations
d) Normal fluctuations
e) Irregular fluctuations
On discovering an improperly adjusted drill press, Jack Joyner, Director of Quality
Control, ordered an inspection of every fifth casting drilled during the evening shift.
Jack is ordering a ___________________.
a) statistic from the castings
b) census of the castings
c) sample of the castings
d) sorting of the castings
e) parameter of the castings
According to the central limit theorem, for samples of size 169 drawn from a population
with µ = 1,014 and = 65, the standard deviation of the sampling distribution
of sample means would equal _______.
a) 1,014
b) 65
c) 15
d) 6
e) 5
In an autoregressive forecasting model, the independent variable(s) is (are) ______.
a) time-lagged values of the dependent variable
b) first-order differences of the dependent variable
c) second-order, or higher, differences of the dependent variable
d) first-order quotients of the dependent variable
e) time-lagged values of the independent variable
Which of the following conditions is not a condition for the hypergeometric
distribution?
a) the probability of success is the same on each trial
b) sampling is done without replacement
c) there are only two possible outcomes
d) trials are dependent
e) n < 5%N
A researcher wants to estimate the difference in the means of two populations. A
random sample of 36 items from the first population results in a sample mean of 430. A
random sample of 49 items from the second population results in a sample mean of 460.
The population standard deviations are 120 for the first population and 140 for the
second population. From this information, a 95% confidence interval for the difference
in population means is _______.
a) -95.90 to 35.90
b) -85.44, 25.44
c) -76.53 to 16.53
d) -102.83 to 42.43
e) 98.45 to 125.48
A gasoline distributor wonders whether an individual’s income level influences the
grade of gasoline purchased. The following is a contingency table from a random
sample of 300 individuals.
The null hypothesis is ______________.
a) “income” is independent of “type of gasoline”
b) “income” influences “type of gasoline”
c) “income” is not independent of “type of gasoline”
d) “income” is related to “type of gasoline”
e) “regular” is independent of “premium”
Sami Schmitt believes that number of cars arriving at his Scrub and Shine Car Wash
follow a Poisson distribution. He collected a random sample and constructed the
following frequency distribution to test his hypothesis.
Using
= 0.05, the critical value of chi-square for this goodness-of-fit test is ____.
a) 9.49
b) 7.81
c) 7.78
d) 11.07
e) 12.77
The mean life of a particular brand of light bulb is 1200 hours and the standard
deviation is 50 hours. It can be concluded that at least 89% of this brand of bulbs will
last between _______.
a) 1100 and 1300 hours
b) 1150 and 1250 hours
c) 1050 and 1350 hours
d) 1000 and 1400 hours
e) 950 and 1450 hours
A statistics student made the following grades on 7 tests: 76, 82, 92, 95, 79, 86, and 92.
What is the mean grade?
a) 78
b) 80
c) 86
d) 84
e) 88
Use the following set of observed frequencies to test the independence of the two
variables. Variable one has values of ‘A’ and ‘B’; variable two has values of ‘C’, ‘D’, and
‘E’.
Using
= 0.05, the estimates of the expected frequency in row 1 (A) column 1 (C)
when the two variables are independent is _______.
a) 9.6
b) 12
c) 16
d) 10
e) 20
While reviewing staffing plans for a new pilot plant, Colin Chenaux, VP of Operations
at Clovis Chemicals, Inc., designed an experiment to test the effects of “supervisor’s
style” and “training method” on the productivity of operators. The treatment levels
were: (1) authoritarian, and participatory for supervisor’s style, and (2) technical
manuals, training films, and multimedia for training method. Three qualified applicants
were randomly selected and assigned to each of the six cells. Analysis of Colin’s data
produced the following ANOVA table.
Using
= .05, the appropriate decision for “supervisor’s style” effects is
_____________.
a) reject the null hypothesis
1
3
b) do not reject the null hypothesis
1
3
c) reject the null hypothesis
1
2
d) do not reject the null hypothesis
1=
2
e) do nothing
Elwin Osbourne, CIO at GFS, Inc., suspects that at least 25% of e-mail messages sent
by GFS employees are not business related. A random sample of 300 e-mail messages
was selected to test this hypothesis at the 0.01 level of significance. Sixty of the
messages were not business related. The appropriate decision is _______.
a) increase the sample size
b) gather more data
c) maintain status quo
d) fail to reject the null hypothesis
e) reject the null hypothesis
Suppose the number of parking spots at urban grocery stores is uniformly distributed
over the interval 90 to 140, inclusively (90 x 140), then the height of this distribution,
f(x), is __________________.
a) 1/90
b) 1/50
c) 1/140
d) 1/200
e) 1/500
A simple regression model developed for ten pairs of data resulted in a sum of squares
of error, SSE = 125. The standard error of the estimate is _______.
a) 12.5
b) 3.5
c) 15.6
d) 3.95
e) 25
Circuit boards for wireless telephones are etched, in an acid bath, in batches of 100
boards. A sample of seven boards is randomly selected from each lot for inspection. A
batch contains two defective boards; and x is the number of defective boards in the
sample. P(x=1) is _______.
a) 0.1315
b) 0.8642
c) 0.0042
d) 0.6134
e) 0.6789
The city golf course is interested in starting a junior golf program. The golf pro has
collected data on the number of youths under 13 that have played golf during the last 4
months. Using a three-month moving average, the forecast value for November in the
following time series would be ____________.
a) 24
b) 21
c) 21.56
d) 19.22
e) 22
Use of a smoothing constant value less than 0.5 in an exponential smoothing model
gives more weight to ___________.
a) the actual value for the current period
b) the actual value for the previous period
c) the forecast for the current period
d) the forecast for the previous period
e) the forecast for the next period
If xis uniformly distributed over the interval 8 to 12, inclusively (8 x 12), then P(x 10)
is __________________.
a) 0.750
b) 0.000
c) 0.333
d) 0.500
e) 0.900
In a set of 25 aluminum castings, four castings are defective (D), and the remaining
twenty-one are good (G). A quality control inspector randomly selects three of the
twenty-five castings without replacement, and classifies each as defective (D) or good
(G). The sample space for this experiment contains ____________ elementary events.
a) 12,650
b) 2,300
c) 455
d) 16
e) 15,6255
Paige DeMarco is the Vice President for University Advancement at State University.
She is responsible for the capital campaign to raise money for the new student services
building. Paige selects the first 100 alumni listed on a web-based social networking site
for State University. She intends to contact these individuals regarding possible
donations. Her sample is a _________.
a) simple random sample
b) stratified sample
c) systematic sample
d) convenience sample
e) cluster sample
The following data is to be used to construct a regression model:
The value of the slope is ____________.
a) 16.49
b) 1.19
c) 1.43
d) 0.75
e) 1.30
Which of the following statements about business statistics is not true?
a) Virtually every area of business uses statistics in decision making.
b) Presenting business statistics always requires the use of a specific graph called a bar
chart.
c) There is a wide variety of uses and applications of statistics in business.
d) Business statistics can be used to forecast future values and predict trends.
A carload of steel rods has arrived at Cybermatic Construction Company. The car
contains 50,000 rods. Claude Ong, manager of Quality Assurance, directs his crew
measure the lengths of 100 randomly selected rods. If the population of rods has a mean
length of 120 inches and a standard deviation of 0.05 inch, the probability that Claude’s
sample has a mean between 119.985 and 120.0125 inches is ____________.
a) 0.9925
b) 0.9974
c) 0.9876
d) 0.9544
e) 0.9044
A researcher wants to know what the average variation is in altimeters of small,
privately owned airplanes. The task of determining this is expensive and time
consuming, if even possible, given the large number of such airplanes. The researcher
decides to use government records to randomly locate the owners of ten such planes
and then get permission to test the altimeters. When the researcher is done, he will use
the data gathered from the group of ten to reach conclusions about all small, privately
owned airplanes. The average variation computed using the data gathered on the group
of ten airplanes is best described as a _______.
a) measurement
b) data
c) statistic
d) parameter.
e) census
Consider the following frequency distribution:
What is the midpoint of the last class interval?
a) 15
b) 350
c) 300
d) 200
e) 400
A company believes that it controls more than 30% of the total market share for one of
its products. To prove this belief, a random sample of 144 purchases of this product is
contacted. It is found that 50 of the 144 purchased this company’s brand of the product.
If a researcher wants to conduct a statistical test for this problem, the alternative
hypothesis would be _______.
a) the population proportion is less than 0.30
b) the population proportion is greater than 0.30
c) the population proportion is not equal to 0.30
d) the population mean is less than 40
e) the population mean is greater than 40
Tamara Hill, fund manager of the Hill Value Fund, manages a portfolio of 250 common
stocks. Tamara is searching for a ‘low risk’ issue to add to the portfolio, i.e., one with a
price variance less than that of the S&P 500 index. Moreover, she assumes an issue is
not ‘low risk’ until demonstrated otherwise. Her staff reported that during the last nine
quarters the price variance for the S&P 500 index (population 1) was 25, and for the last
seven quarters the price variance for XYC common (population 2) was 6. Assume that
stock prices are normally distributed in the population. Using
= 0.05, the appropriate
decision is _______.
a) reject the null hypothesis
b) reject the null hypothesis
c) do not reject the null hypothesis
d) do not reject the null hypothesis
e) maintain status quo
Consider the following sample space, S, and several events defined on it. S = {Albert,
Betty, Abel, Jack, Patty, Meagan}, and the events are: F = {Betty, Patty, Meagan}, H =
{Abel, Meagan}, and P = {Betty, Abel}. The complement of F is ___________.
a) {Albert, Betty, Jack, Patty}
b) {Betty, Patty, Meagan}
c) {Albert, Abel, Jack}
d) {Betty, Abel}
e) {Meagan}
Anita Cruz recently assumed responsibility for a large investment portfolio. She
wonders whether industry sector influences investment objective. Her staff prepared the
following contingency table from a random sample of 200 common stocks.
Using
= .01, observed chi-square value is ______________.
a) 24.93
b) 8.17
c) 32.89
d) 6.59
e) 4.89