EXERCISE 5 Let Mxi,x2 (t1,t2) be the moment generating function of the bivariate normal distribution Show...
Problem 1. (Bivariate Normal Distribution) Let Z1, Z2 be i.i.d. N(0,1) distributed random variables, and p be a constant between –1 and 1. define X1, X2 as: x3 = + VF5223X = v T14:21 - VF52 23 1) Show that, (X1, X2)T follows bivariate Normal distribution, find out the mean vector and the covariance matrix. 2) Write down the moment generating function, and show that when p= 0, X11X2.
4. The moment generating function of the normal distribution with parameters μ and σ2 is (t) exp ( μ1+ σ2t2 ) for -oo < t oo. Show that E X)-ψ(0)-μ and Var(X)-ψ"(0)-[ty(0)12-σ2. 5. Suppose that X1, X2, and X3 are independent random variables such that E[X]0 and ElX 1 for i-12,3. Find the value of E[LX? (2X1 X3)2] 6. Suppose that X and Y are random variables such that Var(X)-Var(Y)-2 and Cov(X, Y)- 1. Find the value of Var(3X -...
Exercise 1 Let X be a random variable that has moment generating function My(t) = 0.5-t2-t Find P[-1<x< 1]
Let ? have a Poisson(?) distribution. (a) Show that the moment generating function (mgf) of ? is given by ?(?) = exp[?(?? − 1)]. (b) Use the mgf found in (a) to verify that ?[?] = ? and ?[?] = ?.
Can we find this without use of the moment generating function? 3. (15 pts) Let Xị and X2 be two independent random variables that follow standard normal distribution. The PDF of a standard normal distribution is given by f(t)= exp-/2; - <t<0.. i) Find the joint PDF of V = X1 + X2 and Y2 = X1 - X). ii) Prove that Yi and Y2 are independent. R ONALEN SON
5 (10 points) X and Y are independent random variables with common moment generating function M(t) eT. Let W X + Y and Z X - Y. Determine the joint moment generating function, M(ti, t2) of W and Z Find the moment generating function of W and Z, respectively
The moment generating function (MGF) for a certain probability distribution is given by 2 (2 + 2) , M(t) = R. t 2 Suppose Xi, X2, are iid random variables with this distribution. Let Sn -Xi+ (a) Show that Var(X) =3/2, i = 1,2. (b) Give the MGF of Sn/v3n/2. (c) Evaluate the limit of the MGF in (b) for n → 0. The moment generating function (MGF) for a certain probability distribution is given by 2 (2 + 2)...
9 Let Xi, X2, ..., Xn be an independent trials process with normal density of mean 1 and variance 2. Find the moment generating function for (a) X (b) S2 =X1 + X2 . (c) Sn=X1+X2 + . . . + Xn. (d) An -Sn/n 9 Let Xi, X2, ..., Xn be an independent trials process with normal density of mean 1 and variance 2. Find the moment generating function for (a) X (b) S2 =X1 + X2 . (c)...
3. Let (X. X2) be standard bivariate normal with p = 3/5. Let (Y.Y2) be the midterm and final exam scores of a randomly selected student. Assume Y1 = 80 +3X1Y2 = 75 + 2X2. Given a student got 90 in the midterm exam, (a) What is the conditional expectation and conditional variance of her final exam score? Hint. Probably easier to reduce the question to (X1, X2) but also (Y1. Y2) is a normal bivariate. (b) What is the...
(a) Show that (Xi, X2) has a bivariate normal distribution with means μ1 , μ2, variances 어 and 05, and correlation coefficient ρ if and only if every linear combination c Xc2X2 has a univariate normal distr bution with mean c1μι-c2μ2, and variance c?σ? + c3- +2c1c2ρσ12, where cı and c2 are real constants, not both equal to zero. (b) Let Yİ = Xi/ởi, i = 1,2. Show that Var(Y-Yo) = 2(1-2).