The classification of student designation (freshman, sophomore, junior, senior)
is an example of
a discrete random variable.
a categorical random variable.
a parameter.
an estimation.
When extreme values are present in a set of data, which of the following
descriptive summary measures are most appropriate?
Interquartile range and median.
variance and CV.
CV and range.
mean and standard deviation.
The dean mailed a survey to a total of 500 students. The sample included 125
students randomly selected from each of the freshman, sophomore, junior, and
senior classes on campus last term. What sampling method was used?
simple random sample.
systematic sample.
cluster sample.
stratified sample.
The joint probabilities shown in a table with two rows, A1 and A2 and two
columns, B1 and B2 , are the following: P(A1 and B1) = 0.1 , P(A1 and
B2 ) =0.3 , P(A2 and B1 ) =0.05 , and P(A2 and B2 ) =0.55 . Then
P(A1 |B1 ) is
0.1
0.25
0.33
0.67
A certain electronic system contains 10 components. Suppose that the
probability that each individual component fail is 0.2 and that the components
fail independently of each other (Bernoulli trial). Given that at least one of the
components has failed, what is the probability that at least two of the
components have failed?
0.2684
0.4247
0.6993
0.8926
On average, 20% of the emergency room patients at a hospital are students.
In a random sample of four patients, what is the probability that three of
them are students?
0
0.0064
0.016
0.0256
In a shipment of 10 mobile phones, 2 are damaged and 8 are good. If you take
a random sample of three mobile phones from the 10 phones, what is the
probability that all of them are in good condition?
0.467
0.512
0.541
0.7
Cars arrive at a gas station at a mean rate of 1.7 cars per minute. What is the
probability of observing no car arriving at the gas station within a period of 60
seconds?
0
0.1827
0.2804
0.5882
After a fierce campaign for launching a new product, an advertiser would like
to estimate the awareness rate of the new product to within 5 percent with
95% confidence. A random sample will be drawn from the target customers.
The sample size for this task should be at least
192
385
625
1060
When the necessary conditions are met, a two-tail test is being conducted to
test the difference between two population proportions, but your statistical
software provides only a one-tail area of 0.058 as part of its output. The
p-value for this test should be
0.029
0.058
0.116
0.942
After calculating the sample size needed to estimate a population proportion
to within 0.05, you have been told that the maximum allowable error must be
reduced to 0.025. If the original calculation led to a sample size of 1000, the
sample size will now have to be
500
2000
4000
8000
In testing the null hypothesis H0 : p1 − p2 = 0 , if H0 is false, the test could
lead to
a Type I error.
a Type II error.
both Type I error and Type II error.
neither a Type I error nor a Type II error.
The lower limit of a confidence interval at 95% level of confidence for the
population proportion if a sample of size 200 had 40 successes is
0.1254
0.1446
0.1535
0.2465
For a given sample size, if the level of significance α is decreased, the power
of the test
will decrease.
will increase.
will remain the same.
cannot be determined.
A 98% confidence interval estimate for a population mean is determined to be
75.38 to 86.52. If the confidence level is reduced to 95%, the confidence
interval for the population mean
becomes narrower.
becomes wider.
remain the same.
none of the above.
In developing an interval estimate for a population mean, the population
standard deviation σ was assumed to be 10. The interval estimate was
50.92 ± 2.14. Had σ equaled 20, the interval estimate would be
50.92 ±1.07
50.92 ± 4.28
50.92 ±8.56
101.84 ± 8.56
Two samples are selected at random from two independent normally
distributed populations. Sample 1 has 49 observations and has a mean of 10
and a standard deviation of 5. Sample 2 has 36 observations and has a mean
of 12 and a standard deviation of 3. The standard error of the sampling
distribution of the sample mean difference is
0.1853
0.4306
0.7331
0.8719
The manager of a department store is thinking about establishing a new
billing system for the store’s credit customers. She determines that the new
system will be cost-effective only if the mean monthly account is more than
$170 at a 5% significant level. A random sample of 400 monthly accounts is
drawn, for which the sample mean is $178. The manager knows that the
accounts are approximately normally distributed with standard deviation of
$65. What is the approximate probability of a Type II error in this case if the
actual mean account is 188?
0
0.05
0.10
0.18
A sample of size 100 selected from one population has 60 successes, and a
sample of size 150 selected from a second population has 95 successes. The
test statistic for testing the equality of the population proportions equal to
–0.5319
0.7293
–0.4190
0.2702
What is the critical value for testing Factor A?
4.74
5.14
5.79
6.94
The conclusion is that
All the results are significant.
Except the type of program, type of sex and interaction are significant.
Except the type of sex, type of program and interaction are significant.
Except the interaction, type of program and sex are significant.
None of the above answers is correct.
Application of the least squares method results in values of the Y intercept
and the slope which minimizes the sum of the squared deviations between
the observed values of the independent variable and the estimated values
of the independent variable.
the actual values of the independent variable and estimated values of the
dependent variable.
the observed values of the dependent variable and the estimated values of
the dependent variable.
None of the above answers is correct.
Larger values of r2 imply that the observations are more closely grouped
about
the average value of the independent variables.
the average value of the dependent variables.
the least squares line.
the origin.
None of the above answers is correct.
In simple linear regression analysis, which of the following is not true?
The F test and the t test yield the same results.
The F test and the t test may or may not yield the same results.
The relationship between X and Y is represented by means of a
straight line.
The value of F = t2 .
None of the above answers is correct.
In a regression and correlation analysis if r2 = 1 , then
SSE must also be equal to one.
SSE must also be equal to zero.
SSE can be any positive value.
SSE must be negative.
None of the above answers is correct.
In regression analysis, an outlier is an observation whose
mean is larger than the standard deviation.
residual is zero.
mean is zero.
residual is much larger than the rest of the residual values.
A sample of 30 houses which were sold in the last year was taken. The value of the
house (Y ) was estimated. The independent variables included in the analysis
were the number of rooms (X1 ) , the size of the lot (X 2 ) , the number of
bathrooms (X3 ) , and a dummy variable (X4 ) , which equals 1 if the house has a
garage and equals 0 if the house dose not have a garage. The following results
were obtained: (α = .05 )
What is the value of multiple coefficient of determination?
0.4979
0.5020
0.992
6.2
None of the above answers is correct.
A sample of 30 houses which were sold in the last year was taken. The value of the
house (Y ) was estimated. The independent variables included in the analysis
were the number of rooms (X1 ) , the size of the lot (X 2 ) , the number of
bathrooms (X3 ) , and a dummy variable (X4 ) , which equals 1 if the house has a
garage and equals 0 if the house dose not have a garage. The following results
were obtained: (α = .05 )
What are the value of “A” and “B”?
5, 24
5, 25
4, 25
4, 26
None of the above answers is correct.
Which description below is wrong?
F test for the model is significant.
X1 a significant factor to predict Y .
X2 a significant factor to predict Y .
X3 a significant factor to predict Y .
X4 a significant factor to predict Y .
In multiple regression analysis, the word linear in the term “general linear
model” refers to the fact that
the relationship between the Y and Xi s is linear.
None of the above answers is correct.
Which of the following tests is used to determine whether an additional
variable makes a significant contribution to a multiple regression model?
a t test.
a Z test.
an F test.
a chi-square test.
None of the above answers is correct.
first-order model with one predictor variable.
second-order model with two predictor variables.
second-order model with one predictor variable.
None of the above answers is correct.
When dealing with the problem of nonconstant variance, the reciprocal
transformation means using
1/ X as the independent variable instead of X .
X2 as the independent variable instead of X .
Y2 as the dependent variable instead of Y .
1/Y as the dependent variable instead of Y .
None of the above answers is correct.
A nonparametric test for the equivalence of two populations would be used
instead of a parametric test for the equivalence of the population parameters
if
the sample are very large.
the samples are not independent.
no information about the population is available.
The parametric test is always used in this situation.
None of the above answers is correct.
Forty-one individuals from a sample of 60 indicated they oppose abortion. We are
interested in determining whether or not there is a significant difference between
the proportions of opponents and proponents of legalized abortion.
The null hypothesis that is being tested is
H0 : μ = 5
H0 : μ = 0.5
H0 : P = 5
H0 : P = 0.5
None of the above answers is correct.
Forty-one individuals from a sample of 60 indicated they oppose abortion. We are
interested in determining whether or not there is a significant difference between
the proportions of opponents and proponents of legalized abortion.
The test statistics is
3.87
2.84
60
0.5
0.68
The conclusion is that.
there is no significant difference between the proportions.
there is a significant difference between the proportions.
there could be a difference in proportions, depending on the sample size.
None of the above answers is correct.
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