If X ~ N(0,1) , then P(−2 ≤ X ≤1) is equivalent to
P(X ≤1) − P(X ≤ −2)
P(X ≤1) + P(X ≥ −2) −1
1− P(X ≥1) − P(X ≤ −2)
1− P(X ≥ 2) − P(X ≤ −1)
All of above
If X and Y are random variables with V (X ) = 7.5 , V (Y) = 6 and
COV (X ,Y) = 4, then V (2X + 3Y) is:
33
37
88
132
Of the last 500 customers entering a supermarket, 50 have purchased a wireless
phone. If the classical approach for assigning probabilities is used, the
probability that the next customer will purchase a wireless phone is
0.10
0.90
0.50
None of the above answers is correct
If X and Y are any random variables, which of the following identities is
not always true?
E(X +Y) = E(X ) + E(Y)
V (X +Y) =V (X ) +V (Y)
E(4X + 5Y) = 4E(X ) + 5E(Y)
V (4X + 5Y) =16V (X ) + 25V (Y) + 40COV (X ,Y)
Which of the following is not true for ah exponential distribution with
parameter λ ?
μ =1 λ
σ =1 λ
The distribution is completely determined once the value of λ is known
The distribution is a two-parameter distribution since the mean and standard
deviation are equal
A larger standard deviation of a normal distribution indicates that the
distribution becomes
narrower and more peaked
flatter and wider
more skewed to the right
more skewed to the left
Which of the following cannot generate a Poisson distribution?
The number of children watching a movie
The number of telephone calls received by a switchboard in a specified time
period
The number of customers arriving at a gas station in Christmas day
The number of bacteria found in a cubic yard of soil
If A and B are independent events with P(A) = 0.60 and P(B) = 0.70, then
the probability that A occurs or B occurs or both occur is
1.30
0.88
0.42
0.10
Which of the following summary measures is affected most by outliers?
The median
The geometric mean
The range
The interquartile range
All of the above
If we want to provide a 95% confidence interval for the mean of a population,
the confidence coefficient is
0.485
1.96
0.95
1.645
As the sample size increases, the margin of error
increases
decreases
stays the same
increases or decreases depending on the size of the mean
For a lower tail test, the p-value is the probability of obtaining a value for the
test statistic
at least as small as that provided by the sample
at least as large as that provided by the sample
at least as small as that provided by the population
at least as large as that provided by the population
An important application of the chi-square distribution is
making inferences about a single population variance
testing for goodness of fit
testing for the independence of two variables
All of these alternatives are correct.
In the analysis of variance procedure (ANOVA), “factor” refers to
the dependent variable
the independent variable
different levels of a treatment
the critical value of F
A least squares regression line
may be used to predict a value of y if the corresponding x value is given
implies a cause-effect relationship between x and y
can only be determined if a good linear relationship exists between x and y
None of these alternatives is correct.
If there is a very weak correlation between two variables, then the coefficient
of determination must be
much larger than 1, if the correlation is positive
much smaller than 1, if the correlation is negative
much larger than one
None of these alternatives is correct.
In a simple linear regression, if the coefficient of correlation is a positive value,
then the slope of the regression line
must also be positive
can be either negative or positive
can be zero
can not be zero
Serial correlation is
the correlation between serial numbers of products
the same as autocorrelation
the same as leverage
None of these alternatives is correct.
impossible to occur
called interaction
called multicollinearity effect
called transformation effect
If the coefficient of determination is 0.64, the coefficient of correlation. What
is the coefficient of correlation? (3%)
The grade point averages of 352 students who completed a college course in
financial accounting have a standard deviation of 90. The grade point averages
of 73 students who dropped out of the same course have a standard deviation of
75. Do the data indicate a difference between the variances of grade point
averages for students who completed a financial accounting course and
students who dropped out? Use a 0.5 level of significance.
Note: F0.25 with 351 and 72 degrees of freedom is 1.466. (5%)
Explain “level of significance” and the “level of confidence.” (6%)
The joint probability distribution of X and Y is shown in the
accompanying table. (10 points in total)
(1) Calculate E(XY) . (5%)
(2) Determine the marginal probability distributions of X and Y . (5%)
可觀看題目詳解,並提供模擬測驗!(免費會員無法觀看研究所試題解答)