E(Z) = E(XY)
= E(X)E(Y) {since X and Y are independent }
=
E to sinple rtamc e one oe ius3diplcment of top storey Y is the sum of the displacements of indiv...
.4 In a simple frame structure such as the one shown in Figure 3.1, the total horizontal displacement of top storey Y is the sum of the displacements of individual storeys Xl and X2. Assume that Xi and X2 are independent and letmxmx and oi, be their respective means and variances. (a) Find the mean and variance of Y (b) Find the correlation coefficient between X2 and 1Y Figure 3.1 Frame structure, for Problem 3.5
.4 In a simple frame...
Let X1, X2, X3 be independent random variables with E(X1) = 1, E(X2) = 2 and E(X3) = 3. Let Y = 3X1 − 2X2 + X3. Find E(Y ), Var(Y ) in the following examples. X1, X2, X3 are Poisson. [Recall that the variance of Poisson(λ) is λ.] X1, X2, X3 are normal, with respective variances σ12 = 1, σ2 = 3, σ32 = 5. Find P(0 ≤ Y ≤ 5). [Recall that any linear combination of independent normal...
topic: model selection on applied linear regression
Exercise 5.5.3 LetY (6,8,9,4,4,4,4,4), X1 (3,0,6,2,4,7,0,0), X2 Consider the regression model Y-k) + Xi A +X2β2+ e, e ~ N (0 (3,0,6,2,4,7,7,0) , σ2 18). i) Find the VIFs for Xi and X2. ii) Estimate β1, β2 and find the variances of the estimates in terms of σ2 iii) Estimate σ2. iv) Find X3, which is a unit vector in the span of Xi,X2 but is orthogonal to X2 (Hints: consider (In-Ho)Xi for...
Let X1 and X2 be independent random variables with means μ1 and μ2, and variances σ21 and σ22, respectively. Find the correlation of X1 and X1 + X2. Note that: The covariance of random variables X; Y is dened by Cov(X; Y ) = E[(X - E(X))(Y - E(Y ))]. The correlation of X; Y is dened by Corr(X; Y ) =Cov(X; Y ) / √ Var(X)Var(Y )
Given random variables X1, X2, Y with E[Y | X1, X2] =
5X1 + X1X2 and E[Y
2
| X1, X2] =
25X2
1X2
2 + 15, find
E[(X1Y + X2)
2
| X1, X2].
ㄨ竺Bin(2.1/4). Suppose X and Y are independent random variables. Find the expected value of YX. Hnt: Consider conditioning on the events (X-j)oj0,1,2. 9. Given random variables XI,X2, Y with E'Y | XiN;|-5X1 + X1X2 and Ep2 1 X1,X2] 25XX15, find 10. Let X and Y...
Two random variables X and Y have means E[X] = 1 and E[Y] = 0, variances 0x2 = 9 and Oy2 = 4, and a correlation coefficient xx =0.6. New random variables are defined by V = -2X + Y W = 2X + 2Y Find the means of V and W Find the variances of V and W defined in question 3 Find Rww for the variables V and W defined in question 3
Random variable
(20) Z X+Y is a random variable equal to the sum of two continuous random variables X and Y. X has a uniform density from (-1, 1), and Y has a uniform density from (0, 2). X and Y may or may not be independent. Answer these two separate questions a). Given that the correlation coefficient between X and Y is 0, find the probability density function f7(z) and the variance o7. b). Given that the correlation coefficient...
Let X1 d = R(0,1) and X2 d= Bernoulli(1/3) be two independent random variables, define Y := X1 + X2 and U := X1X2. (a) Find the state space of Y and derive the cdf FY and pdf fY of Y . (You may wish to use {X2 = i}, i = 0,1, as a partition and apply the total probability formula.) (b) Compute the mean and variance of Y in two different ways, one is through the pdf of...
Problem D: Suppose X1, .,X, are independent random variables. Let Y be their sum, that is Y 1Xi Find/prove the mgf of Y and find E(Y), Var(Y), and P (8 Y 9) if a) X1,.,X4 are Poisson random variables with means 5, 1,4, and 2, respectively. b) [separately from part a)] X,., X4 are Geometric random variables with p 3/4. i=1
Let X1 d= R(0,1) and X2 d= Bernoulli(1/3) be two independent random variables, define Y := X1 + X2 and U := X1X2. (a) Find the state space of Y and derive the cdf FY and pdf fY of Y . (You may wish to use {X2 = i}, i = 0,1, as a partition and apply the total probability formula.) (b) Compute the mean and variance of Y in two different ways, one is through the pdf of Y...