Prob and Stat Homework 6
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Homework 6
Problem 1
Calculate EX and varX and the MGF of X when X ∼ U[a, b]. And derive EX and varX through MGF instead of directly integrating pdf.
Problem 2
Starting from the density function of the normal distribution N(µ, σ2), verify that the parameters µ and σ2 are indeed the mean and variance of this normal distribution.
Problem 3
Suppose X and Y have the joint PMF
fXY (x, y) = c|x + y| for x = − 1, 0, 1 and y = 0, 1,
where c is an unknown constant.
(1) Obtain the joint PMF table for the bivariate random variable (X, Y), with c involved;
(2) Find the value of c;
(3) Give the supports of X , Y, and (X, Y) respectively;
(4) Compute P(X = 0 and Y = 1);
(5) Compute P(X = 1);
(6) Compute P(|X − Y| ≤ 1).
Problem 4
The Parieto distribution, with parameters α and β, has PDF
f(x) = xβ+1 , α < x < ∞, β > 0, α > 0.
(1) Verify that f(x) is a PDF.
(2) Derive the mean and variance of this distribution.
(3) Prove that the variance does not exist if β ≤ 2.
2021-12-25