Quiz
SCM 200 Final Exam Practice Questions
Questions in this quiz (130)
1We should determine our objectives
of a study before we collect the data.- ATrue
- BFalse
2The numbers on a basketball jersey
are an example of qualitative data.- ATrue
- BFalse
3A cumulative relative frequency
totals to- A0%
- B100%
- CThe total number in your sample (n)
- DCannot be determined without seeing the data
4A data set that is skewed left
(negative) has most of the data
values on the left with a few data
values trailing off to the right.- ATrue
- BFalse
5A descriptive measure of a sample is
a parameter.- ATrue
- BFalse
6A stem and leaf plot is useful
because it- Ashows the distribution of the data
- Bcontains all the original data values
- Cshows the distribution of the data AND contains all the original data values
- Dit is a cumulative distribution
7The first quartile of a distribution can
never be less than zero.- ATrue
- BFalse
8A boxplot is a good way to show the
mean of a data set.- ATrue
- BFalse
9Generally speaking, a stem and leaf
plot cannot be constructed from a
boxplot, but a boxplot can be
constructed from a stem and leaf
plot.- ATrue
- BFalse
10A population consists of the numbers 3,
8, 4. The mean and median, respectively,
are:- A5,8
- B3,8
- C4,5
- D5,4
11The median and mode are not
affected by outlier values.- ATrue
- BFalse
12Every data set has a mode.
- ATrue
- BFalse
13One section of SCM 200 has 20 students,
another has 25 students, and a third
section has 55 students. A weighted
average of the number of students in
these sections is:- A25
- B40.5
- C33-1/3
- D30
14The following measures of variation
measure distance from the mean:- Amean absolute deviation
- Bvariance
- Cinterquartile range
- Dmean absolute deviation AND variance
15Median is a measure of variability of
a data set.- ATrue
- BFalse
16Range is sensitive to all data values.
- ATrue
- BFalse
17If we want the average of all the
deviations from the mean of a data
set, we can simply add the deviations
and divide by n.- ATrue
- BFalse
18The mean absolute deviation of the four
numbers 6, 14, 14, 14 is equal to- A0
- B1
- C2
- D3
19The units of a population mean absolute
deviation for a problem in which the units
are feet are- Afeet squared
- Bthe absolute value of feet
- Cfeet
- Dno units. MAD is a relative measure
20A population has three values: 3, 7, 5.
Find the population variance.- A0
- B2.67
- C1.63
- D4
- E2
21A population consisted of the values 3, 7,
11, 11, 13. The population standard
deviation is equal to:- A12.8
- B3.58
- C16
- D4
22A sample consisting of the numbers 3, 6,
9 has a sample variance equal to 12.- ATrue
- BFalse
23The number of hours a child spent
watching TV over the past three days
was 15, 3, 9. Compute the sample
standard deviation.- A24
- B6
- C3
- D2
24A standard deviation can sometimes be
larger in numerical value than a variance.- ATrue
- BFalse
25The coefficient of variation computed
from the three sample values 25, 30, 35
would be equal to 20.- ATrue
- BFalse
2695% of data values that conform to a bellshaped
distribution lie within how many
standard deviations of the mean?- A0
- B1
- C2
- D3
27Student score = 70
Class mean = 80
Standard deviation = 5
The standard score is equal to 2.- ATrue
- BFalse
28Drawing an ace of spades and a three
of hearts are complementary events.- ATrue
- BFalse
29The items in a sample space must be
- Acomplementary
- Bexhaustive
- Crandom
- Dcomplementary AND exhaustive
30When a probability is described in terms of the proportion of times that and event can be theoretically expected to occur, it is an example of relative frequency probability.
- ATrue
- BFalse
31A couple plans to have 3 children. Assuming male-female births are equally likely, what is the probability that couple will have at least one girl among the three children?
- A1/3
- B2/3
- C3/8
- D7/8
32When one throws a die 1,000 times
and determines that the probability of
obtaining a six on a die is one-sixth,
that person has used the theoretical
approach to probability.- ATrue
- BFalse
33A student has three pairs of socks in her
closet: one black pair, one red pair, and
one white pair. If she randomly selects
two socks from her closet, what is the
probability that they will be the same
color? (i.e. They will be a matching pair.)- A2/3
- B.20
- C.80
- D.75
34The distribution of people’s heights
is an example of a discrete
probability distribution.- ATrue
- BFalse
35The sum of the probabilities in a
discrete probability distribution could
total 1.2.- ATrue
- BFalse
36Probabilities associated with random
variables must all be equal.- ATrue
- BFalse
37A quiz with 10 questions on it was given
to a class of 10 students. Each question
was worth one point and the results are
summarized below:
X = number of correct answers = 10, 9, 8,
7, 6, 5 or less, with frequencies f(X) = 3, 2,
1, 2, 2, 0 respectively.
The quiz score mean (expected value) is:- A8
- B8.2
- C9
- D7.8
38Find the variance of X for the following
probability distribution:
X P(X)
1 .4
3 .2
5 .4- A1.6
- B4
- C8/3
- D3.2
39Find the standard deviation of X for the
following probability distribution:
X P(X)
20 .50
30 .10
60 .40- A4.29
- B18.4
- C19
- D361
40Non-random samples involve
unequal probabilities.- ATrue
- BFalse
41For a random variable X to have a
binomial distribution, it is necessary that:- AX represents the number of successes
- Bthe outcome of each trial is a success
- Cthe n trials are statistically dependent on eachother
- DX represents the number of successes AND the outcome of each trial is a success
42A success in a binomial distribution
indicates that something positive has
occurred.- ATrue
- BFalse
43A weighted die is thrown. Success is
defined as getting an even number.
The probability of success is .55.
The probability of getting 2 even
numbers when throwing the die four
times is approximately .3675.- ATrue
- BFalse
44Samantha calls on 10 houses per day
selling Girl Scout cookies. Historically,
3 out of 4 customers buy cookies.
Assuming the binomial distribution
applies here, the variance of this
distribution is:- A1.875
- B1.37
- C7.5
- D2.5
45The standard deviation of the
distribution in the previous problem
is 1.37.- ATrue
- BFalse
46The standard normal distribution has
a mean of 1 and a standard deviation
of 0.- ATrue
- BFalse
47If X is a normal random variable with
a mean of 10 and a standard
deviation of 1/2, then X = 14 is 8
standard deviations away from the
mean.- ATrue
- BFalse
48Use the standard normal curve to
determine the probability that the random
variable z will fall between –0.04 and 0.44.
That is, find the following probability:
P(–0.04 < z < 0.44):- A.4000
- B.4800
- C.1860
- D.1540
49In the standard normal z-distribution,
the probability between z = –1 and z =
+1 is the same as the probability
between z = –0.5 and z = +1.5.- ATrue
- BFalse
50The lifetime of tires is normally distributed
with a mean of 50,000 miles and a standard
deviation of 3,000 miles. The warranty is
for 46,000 miles. What proportion of the
tires will fail after the warranty but before
52,000 miles? Indicate the interval below
that contains this probability.- A.0000 to .2000
- B.2001 to .4000
- C.6001 to .8000
- D.8001 to 1.000
- E.4001 to .6000
51When 6.3% of the data values fall
below a normally distributed random
variable, the correct z-value is -1.53.- ATrue
- BFalse
52Weights of cereal boxes are normally
distributed with a mean of 15 oz. and a
standard deviation of .5 oz. What is the
minimum weight a box could be and
remain in the top 14.46% of all boxes
filled?- A16.10 oz.
- B14.47 oz.
- C15.53 oz.
- DThe answer cannot be determined with the information given
53An unbiased estimator is:
- A no more likely to be above the
population parameter than below. - B always better than a biased
estimator. - C is a specific observed value of a
statistic. - Dalways better than a biased
estimator AND is a specific
observed value of a statistic.
- A no more likely to be above the
54The sample range is generally an
unbiased estimator of the population
range.- ATrue
- BFalse
55A disadvantage of a point estimate is
that we don’t know how accurate that
estimate is.- ATrue
- BFalse
56A sampling distribution is a
distribution of all possible values of a
statistic for a given sample size.- ATrue
- BFalse
57All standard deviations are standard
errors, but not all standard errors are
standard deviations.- ATrue
- BFalse
58If a random sample of size 16 is taken
from a skewed population whose mean is
equal to 360 and standard deviation is 36,
the standard error of the mean would
equal:- A9
- B90
- C10
- D1/9
59Given a population standard
deviation, as sample size increases,
standard error also increases.- ATrue
- BFalse
60For a test, the pop. mean score is 1100 and
the pop. st. dev. is 100. If the test is given
to 36 randomly selected individuals, what
is the probability that the sample mean will
lie between 1090 and 1122? After finding
the appropriate probability, indicate the
interval that includes this probability:- A.0000 to .3000
- B.8501 to 1.000
- C.6001 to .7000
- D.3001 to .6000
- E.7001 to .8500
61The Central Limit Theorem assures
us that the sampling distribution for
the sample mean approaches a
normal distribution as the sample
size increases, regardless of the
shape of the population distribution.- ATrue
- BFalse
62Records have shown that 15% of patients
are not satisfied with their care. A poll of
100 patients was conducted. What is the
probability that more than 18 patients will
not be satisfied with their care? After
finding the probability, indicate the
interval that includes this probability.- A.0000 to .3000
- B.8501 to 1.000
- C.6001 to .7000
- D.3001 to .6000
- E.7001 to .8500
63Confidence intervals specify
parameter values in advance.- ATrue
- BFalse
64In using the standard normal distribution
to establish a confidence interval for the
average number of hours that a light bulb
will last, what is the appropriate z-value to
use for a 34% level of confidence:- A0.17
- B0.1331
- C0.44
- D0.99
65Other things being equal, a 90%
confidence interval is wider than a
95% confidence interval.- ATrue
- BFalse
66A bank wants to determine mean waiting
time. It samples 100 customers and the
mean time is 6.9 minutes. Population
standard deviation is assumed to be 4
minutes. Find a 91.98% confidence
interval of mean waiting time:- A 6.9 +/- 0.7
- B6.9 +/- 0.92
- C6.9 +/- 0.5
- D6.9 +/- 1.75
67A t-distribution with 5 degrees of
freedom has less area in the tails
than a standard normal distribution.- ATrue
- BFalse
68The following is true about the t-distribution:
- Alike the standard normal distribution, there is only one t-distribution
- Bthe mean is 0
- Cis determined by the parameter mu
- Dapproaches the standard normal as degrees of freedom become smaller
69The important distinction between
the z-statistic and t-statistic is that z
is used for large sample sizes and t is
used for small sample sizes.- ATrue
- BFalse
70A confidence interval for a true population
mean is to be constructed from sample
data with size n = 23. The t-value to use
for setting a 90% level of confidence is:- A1.321
- B1.319
- C1.717
- D1.714
- E1.645
71A random sample of 4 glass rods is tested
and reveals the following breaking
strength in pounds: 8, 4, 2, 6. Construct
an 80% confidence interval for the true
mean breaking strength:- A(1.73, 8.27)
- B(3.74, 6.26)
- C(-.46, 10.46)
- D(2.89, 7.11)
72Increasing the sample size, but using
the same level of confidence,
produces a confidence interval that
has a greater likelihood of containing
the parameter being estimated.- ATrue
- BFalse
73The mean age of viewers of TV shows
interests advertisers. A major network
believes that the mean age of viewers of a
show is more than 30. Many affiliate
stations claim the mean age is not greater
than 30. What is H0 for testing the major
network’s claim. Population mean mu is:- Aless than 30
- Bgreater than 30
- Cnot equal to 30
- Dat least 30
- Eat most 30
74In testing the hypothesis below, a
statistician found that z = -0.44. What is
the p-value?
H0: mu = 10
Ha: mu does not equal 10- A.67
- B.66
- C.56
- D.33
- E.17
75In order to compute the p-value from
sample data, we need to know both
the alternative hypothesis and the
level of significance.- ATrue
- BFalse
76To test that the mean lifetime of light
bulbs is at least 900 hours (pop. normally
distributed and pop. st. dev. is 20), a
random sample of 25 bulbs is tested,
yielding a sample mean of 894 hours.
Find the p-value for the test. Indicate
which interval below contains the p-value.- A.0301 to .1000
- B.5001 to 1.000
- C.2001 to .5000
- D.0000 to .0300
- E.1001 to .2000
77If the p-value for a given hypothesis
testing problem is .055 and the level
of significance is .05, the null
hypothesis should be rejected.- ATrue
- BFalse
78In the following hypothesis test,
H0: mu = 4
Ha: mu > 4
the t-value was computed to be –2
and degrees of freedom are 11. The
correct p-value is .025 < p-value < .05.- ATrue
- BFalse
79Given an upper-tailed t-test for one
mean with 30 degrees of freedom and
the value of the test statistic computed
from the sample data t = 2.75 would
yield a p-value equal to .01.- ATrue
- BFalse
80Four runners were randomly sampled and
it was found they ran 23, 19, 23, and 23
miles per week. If we wish to test the
claim that the population mean running
distance is less than 25 miles per week,
what conclusion should be reached at the
1% level of significance?- AReject the claim by rejecting Ho
- BAccept the claim by rejecting Ho
- CReject the claim by accepting Ho
- DAccept the claim by accepting Ho
81In statistical process control, if the pvalue
is less than or equal to alpha, we
should conclude the process is under
control.- ATrue
- BFalse
82If mu = 40 pounds, sigma = 4 pounds, and
sample size is 36, the LCL and UCL on a
control chart for x would be:- A38 pounds, 42 pounds
- B28 pounds, 52 pounds
- C38.67 pounds, 41.33 pounds
- D35 pounds, 45 pounds
83A poll in a senatorial contest revealed that
40 out of 400 randomly selected people
indicated a preference for candidate A.
Find a 95.44% confidence interval for the
proportion of voters who favor candidate
A.- A.07 to .13
- B.06 to .14
- C.05 to .15
- D.09 to .11
- E.38 to .42
84A promoter is deciding whether to book a
new band. The promoter decides to do a
survey to try to estimate the true
proportion of individuals in the area who
will attend the concert. What should
sample size be to estimate the proportion
to within 5% with a 68.26% confidence
level? (Assume maximum error possible.)- A25
- B100
- C400
- D200
85In selecting a sample size to estimate
a population proportion, the sample
size will depend, among other things,
upon the level of confidence that is to
be used for the estimate.- ATrue
- BFalse
86A company is planning to test whether the
market share of a new product during its
first year on the market is more than 20
percent. The appropriate null hypothesis
would be that the market share percentage
is- Agreater than 20%
- Bless than or equal to 20%
- Cless than 20%
- Dnot equal to 20%
- Egreater than or equal to 20%
87A manufacturer claims that no more than
20% of all units will experience a failure
within the first 5 years. 100 purchasers
randomly selected were asked to report
failures. If 28 failures were reported, what
conclusion should be reached about the
manufacturer’s claim? alpha = 5%.- AAccept the claim by rejecting Ho
- BReject the claim by rejecting Ho
- CAccept the claim by accepting Ho
- DReject the claim by accepting Ho
88Assume for a given hypothesis testing
problem, the test statistic was computed
and led to a rejection of the null at alpha of
.01. Based on this information, we can
further conclude that since H0 was rejected
at the 1% level, then H0- AMust be rejected at alpha of 10%
- Bmust be accepted at alpha of 10%
- Cmust be accepted at alpha of 5%
- Dmust be accepted at alpha of 5% and 10%
89The t-test for n1 = 15 and n2 = 15 using
paired testing has- A14 degrees of freedom
- B13 degrees of freedom
- C29 degrees of freedom
- D28 degrees of freedom
- E30 degrees of freedom
90A paired difference experiment produced
the following data: n = 30, xbar1 = 72, xbar2 = 75.5,
Dbar = -3.5, and SD squared = 17. SE(Dbar) is equal to:- A-0.64
- B0.64
- C0.75
- D-0.75
- E3.10
91Assume a matched pairs test for a
mean difference with a two-tailed
alternative hypothesis and the
number of paired differences n = 4. If
the computed test statistic t = 2.353,
then the p-value would be equal to
.05.- ATrue
- BFalse
92An analyst is testing a new system to see if
it uses a different processing time than the
old system. The time for each in seconds
was recorded for 28 samples.
Old System: mean = 21.2, s = 3.2, n = 28
New System: mean = 24.3, s = 2.1, n = 28
Difference (Old – New): mean = – 3.1,
s = 1.4, n = 28
What is the appropriate statistical test?- APaired t-test for mean differences
- BHypothesis test for one proportion
- Cregression analysis
- DIndependent t-test for mean differences
93An analyst is testing a new system to see if
it uses a different processing time than the
old system. The time for each in seconds
was recorded for 28 samples.
Old System: mean = 21.2, s = 3.2, n = 28
New System: mean = 24.3, s = 2.1, n = 28
Difference (Old – New): mean = – 3.1,
s = 1.4, n = 28
What is the alternative hypothesis for the
question above?- AHa: muD = 0
- BHa: MuD < 0
- CHa: MuD > 0
- DHa: MuD does not equal 0
94In a simple linear regression analysis,
the p-value associated with a test of
the slope coefficient was equal to .026,
which would lead us to conclude that a
linear relationship exists between the
two variables at the 5% level of
significance.- ATrue
- BFalse
95An analyst is testing a new system to see if
it uses a different processing time than the
old system. The time for each in seconds
was recorded for 28 samples.
Old System: mean = 21.2, s = 3.2, n = 28
New System: mean = 24.3, s = 2.1, n = 28
Difference (Old – New): mean = – 3.1,
s = 1.4, n = 28
The correct t-value for the previous
question is:- A62
- B11.72
- C-62
- D-11.72
96An analyst is testing a new system to see if
it uses a different processing time than the
old system. The time for each in seconds
was recorded for 28 samples.
Old System: mean = 21.2, s = 3.2, n = 28
New System: mean = 24.3, s = 2.1, n = 28
Difference (Old – New): mean = – 3.1,
s = 1.4, n = 28
If the p-value for this test is less than .002
and alpha is .05, analysts would conclude
that- Athe old system uses more processing time
- Bthe old system uses less processing time
- Cthe systems use the same processing time
- Dthe system processing times are unequal
97A doctor claims the average person is
more than 11 pounds overweight. To test
the claim, the difference between actual
and ideal weight of 36 randomly selected
people was calculated. The sample mean
and sample standard deviation were 14
and 5 pounds respectively. At alpha of 1%,
can we conclude the claim is true?- AYes, the claim is true by rejecting Ho
- BYes, the claim is true by accepting Ho
- CNo, the claim is not true by rejecting Ho
- DNo, the claim is not true by accepting Ho
98The difference between the
independent sample and paired
sample approach is that with the
independent sample approach, a
background variable's effect is
controlled by pairing.- ATrue
- BFalse
99In general, the paired samples
method is preferred over the
independent samples method.- ATrue
- BFalse
100The t-test for n1 = 15 and n2 = 7 using the
independent samples approach has
(assuming equal population variances)- A14 degrees of freedom
- B6 degrees of freedom
- C21 degrees of freedom
- D20 degrees of freedom
- E22 degrees of freedom
101Given the following information about a
hypothesis test of the difference between
two means based on independent random
samples. (Assume normal distributions
with equal variances.) The correct pvalue
is between .005 and .01.
H0: μ1 – μ2 = 0
Ha: μ1 – μ2 ≠ 0
x1 = 16.32, x2 = 17.44,
s1squared = 4.3,
s2squared = 2.2,
n1 = 30, n2 = 32- ATrue
- BFalse
102The best statistic for pi1 - pi2 is p1 – p2.
- ATrue
- BFalse
103For n1 = 70 and n2 = 100 from populations
1 and 2, the number of successes are 35
and 35 respectively. The estimate of the
difference between pi1 - pi2 is- A0.35
- B0.15
- C0.70
- D0.50
- E0.42
104For n1 = 200 and n2 = 100 from
populations 1 and 2, the numbers of
successes are 35 and 25 respectively.
The value of the pooled sample
proportion p-hat is 0.20.- ATrue
- BFalse
105In an upper-tailed test of the difference
of two proportions, the z-value was
calculated to be 2.69. The p-value for
this test would then be .0036.- ATrue
- BFalse
106The purpose of a scatterplot is to
visually determine if a relationship
exists between two variables.- ATrue
- BFalse
107In using the regression model for
forecasting the next value (or an
individual value) of y, the prediction
interval will be- Athe same as the estimating interval
- Bnarrower than the estimating interval
- Cwider than the estimating interval
- Dwider or narrower, depending on the data
108The coefficient of determination (R2) is
equal to 0.64, and the linear regression
equation which indicates an inverse
relationship between x and y is equal to
ŷ = 2 - .74x, then the correlation coefficient
must necessarily be equal to:- A-.80
- B+.64
- C-.74
- Deither -.80 or +.80
109In a simple linear regression and
correlation problem, a correlation
coefficient of .80 means that 64% of
the variation in y can be explained by
x.- ATrue
- BFalse
110When R2 = 1, then Se = Sy.
- ATrue
- BFalse
111A correlation coefficient of –1.0 would
imply that the standard error of the
estimate Se would necessarily be equal
to 0.- ATrue
- BFalse
112Standard error is measured in the units
of the x variable.- ATrue
- BFalse
113The range of a regression coefficient is
– 1 to + 1.- ATrue
- BFalse
114Standard deviation of height = 2.45
inches.
Standard deviation of weight = 23
pounds.
Correlation = .56
If we are predicting weight from height,
the regression coefficient is 5.26.- ATrue
- BFalse
115If ŷ = 15 + 10x, then the estimated value of
y when x = 5 is:- A25
- B65
- C10
- D15
- E55
116When H0 is accepted in a regression
model, we conclude:- A A linear relationship exists
between x and y. - BThe x variable is statistically
significant. - CThe x variable is not statistically
significant. - DA linear relationship exists
between x and y AND the x
variable is statistically significant.
- A A linear relationship exists
117Seasonality can be incorporated into
regression models with dummy
variables.- ATrue
- BFalse
118For the linear equation ŷ = 50 – 2x where y
is the number of items sold and x is the
price of the product in $, which is true?- A The equation represents an inverse
relationship between y and x. - BThe equation represents a positive
relationship between y and x
because the constant term 50 is
greater than 0. - CThe slope of the line is – 2 dollars
per each item sold. - DThe slope of the line is +50 dollars
per each item sold.
- A The equation represents an inverse
119If a correlation exists between y and x,
then necessarily either y causes x or x
causes y.- ATrue
- BFalse
120The advantage of multiple regression
over simple regression is that we can
change more than one variable at a
time.- ATrue
- BFalse
121If ŷ = 31 + 1.2x1 – 3.4x2 + 5x3, then the
estimated value of y when x1 = – 6, x2 = 3,
and x3 = 2 is:- A31.7
- B25.4
- C23.6
- D38
122The alternative hypothesis in a multiple
regression problem is that no linear
relationship exists between a given
independent variable and y.- ATrue
- BFalse
123The correlation coefficient between college
GPA and H.S. GPA is .70. The correlation
coefficient between college GPA and H.S.
rank is .60. Which of the following is true?- A70% of the variation in college GPA can
be explained by H.S. GPA. - B60% of the variation in college GPA can
be explained by H.S. GPA. - CH.S. GPA is a better predictor of college
GPA than H.S. rank. - DThere is an inverse relationship between
H.S. GPA and College GPA.
- A70% of the variation in college GPA can
124Adding another variable to a regression
equation will make R2- Adecrease
- Bincrease
- Cstay the same or increase
- Dstay the same or decrease
- Eincrease, decrease, or stay the same
125The purpose of R2 adjusted is to
discern the effect of adding a variable
to a model.- ATrue
- BFalse
126Adding another variable to a
regression equation will necessarily
make R2 adjusted increase.- ATrue
- BFalse
127It is possible for a variable to be
significant in multiple regression when
that same variable is not significant in
simple regression.- ATrue
- BFalse
128Stable environments are critical for
effective time series analysis.- ATrue
- BFalse
129Which of the following is not a component
of time series?- ASeasonality
- BCycle
- CRandomness
- DTrend
- EContingency
130The regression model based on annual
data for the last 20 years is
ŷ = 20.35 + 2.4x. The actual value of y
when x = 12 is 52. The value of the
forecasting error is:- A68.35
- B16.35
- C2.85
- D49.15
- E40
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- Quiz on SCM 200 Final Exam Practice Questions, created by mursham22 on 16/12/2014.
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