Question

Which of the following statements are not true if the probability density function of a continuous random variable X is $f(x) = 5e^{-5x}$, $x \geq 0$? A. E(X) = .02 B. V(X) = .04 C. The cumulative distribution function of X is $F(x) = 1 - e^{-5x}$, $x \geq 0$. D. P(X $\leq$ 1) $\approx$ .9933 E. All of the above statements are not true. Which of the following statements about the percentiles for the standard normal distribution are correct? A. The 90th percentile is approximately -1.28 B. The 10th percentile is approximately 1.28 C. The 75th percentile is approximately .67 D. The 15th percentile is approximately 1.04 E. None of the above answers is correct Which of the following statements are correct about the independence of two random variables? A. Two random variables are independent if their joint probability mass function (pmf) or their joint probability density function (pdf) is the product of the two marginal pmf's or pdf's. B. Independence of two discrete random variables X and Y require that every entry in the joint probability table be the product of the corresponding row and column marginal probabilities. C. Independence of two random variables is most useful when the description of the experiment under study tells us that X and Y have no effect on one another. D. All of the above are correct statements E. Only A and B are correct statements

          Which of the following statements are not true if the probability density function of a continuous random variable X is $f(x) = 5e^{-5x}$, $x \geq 0$?
A. E(X) = .02
B. V(X) = .04
C. The cumulative distribution function of X is $F(x) = 1 - e^{-5x}$, $x \geq 0$.
D. P(X $\leq$ 1) $\approx$ .9933
E. All of the above statements are not true.
Which of the following statements about the percentiles for the standard normal distribution are correct?
A. The 90th percentile is approximately -1.28
B. The 10th percentile is approximately 1.28
C. The 75th percentile is approximately .67
D. The 15th percentile is approximately 1.04
E. None of the above answers is correct
Which of the following statements are correct about the independence of two random variables?
A. Two random variables are independent if their joint probability mass function (pmf) or their joint probability density function (pdf)
is the product of the two marginal pmf's or pdf's.
B. Independence of two discrete random variables X and Y require that every entry in the joint probability table
be the product of the corresponding row and column marginal probabilities.
C. Independence of two random variables is most useful when the description of the experiment under study tells us that X and Y have no effect on one another.
D. All of the above are correct statements
E. Only A and B are correct statements

Which of the following statements are not true if the probability density function of a continuous random variable X is f(x) = 5e^-5x, x ≥ 0?
A. E(X) = .02
B. V(X) = .04
C. The cumulative distribution function of X is F(x) = 1 - e^-5x, x ≥ 0.
D. P(X ≤ 1) ≈ .9933
E. All of the above statements are not true.
Which of the following statements about the percentiles for the standard normal distribution are correct?
A. The 90th percentile is approximately -1.28
B. The 10th percentile is approximately 1.28
C. The 75th percentile is approximately .67
D. The 15th percentile is approximately 1.04
E. None of the above answers is correct
Which of the following statements are correct about the independence of two random variables?
A. Two random variables are independent if their joint probability mass function (pmf) or their joint probability density function (pdf)
is the product of the two marginal pmf's or pdf's.
B. Independence of two discrete random variables X and Y require that every entry in the joint probability table
be the product of the corresponding row and column marginal probabilities.
C. Independence of two random variables is most useful when the description of the experiment under study tells us that X and Y have no effect on one another.
D. All of the above are correct statements
E. Only A and B are correct statements

Added by Ramon M.

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