Homework Answers
TOPIC:Variance,covariance and correlation coefficients between random variables.
![- E (72) - E(y). E (2) . = [(a+bx) (c + dx] - E[a+bx). E CC + 2x). [ac + adx + be * + bd x2 -Cato bec) (c+den = (acht a) + ad](http://img.homeworklib.com/questions/b2d44620-78b8-11ea-8ab2-3fc70901855f.png?x-oss-process=image/resize,w_560)
![and cow (x, y). = Con (x, 0.5 +0.6x). Con (X, 0,5 at Cor (x, 0.6x). = 0 + 0.6. Var (*) [ Cor (x, 0.6x). I (0.6) war (x)] t. T](http://img.homeworklib.com/questions/b4afee00-78b8-11ea-9a61-f5b3e0d5d73d.png?x-oss-process=image/resize,w_560)
(Also,the slope of the equations , Y=0.5+0.6X and Z=0.2+0.3X are positive. Hence,there is a perfectly linear and positive correlation between the variables and hence the correlation coefficients become 1).
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2. Properties of Correlation and Covariance: Two random variables Y and Z are represented by the...
15. The means, standard deviations, and covariance for random variables X, Y. and Z are given...
15. The means, standard deviations, and covariance for random variables X, Y. and Z are given below. x = 3, uy = 5. z = 7 ox= 1, OY = 3, oz = 4 cov(X, Y) = 1, cov (X, Z) = 3, and cov (Y,Z) = -3 T=X-2Y+3 Z var(T) =
Exercise 1 (1). X, Y are random variables (r.v.) and a,b,c,d are values. Complete the formulas...
Exercise 1 (1). X, Y are random variables (r.v.) and a,b,c,d are values. Complete the formulas using the expectations E(X), E(Y), variances Var(X), Var(Y) and covariance Cov(X, Y) (a) E(aX c) (b) Var(aX + c (d) Var(aX bY c) (e) The covariance between aX +c and bY +d, that is, Cov(aX +c,bY +d) f) The correlation between X, Y that is, Corr(X,Y (g) The correlation between aX +c and bY +d, that is, Corr(aX + c, bY +d)
5. The means, standard deviations, and covariance for random variables X, Y, and Z are given...
5. The means, standard deviations, and covariance for random variables X, Y, and Z are given below. Ux= 3, uy = 5, uz = 7 Ox= 1, OY = 3, oz = 4 cov(X, Y) = 1, cov (X, Z) = 3, and cov (Y,Z) = -3 T= X-28 +3 Z var(T) = 16. For a random variable X with an unknown distribution. The mean of X is u = 22 and tting a randomly chosen value of X
5.8.6 otherwise. (a) Find the correlation rx.y (b) Find the covariance Cov(X,Y]. 5.8.6 The random variables...
5.8.6
otherwise. (a) Find the correlation rx.y (b) Find the covariance Cov(X,Y]. 5.8.6 The random variables X and Y have (b) Use part Cov oint PMF (c) Show tha Var[ (d) Combine Px,y and 5.8.10 Ran the joint PM PN,K (n, k) 0 0 Find (a) The expected values E[X] and EY, pected (b) The variances Var(X] and Var[Y],VarlK], E Find the m
Let X1 and X2 be independent random variables with means μ1 and μ2, and variances σ21...
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 )
Prove the following properties using the definition of the variance and the covariance: Q1. Operations with...
Prove the following properties using the definition of the
variance and the covariance:
Q1. Operations with expectation and covariances Recall that the variance of randon variable X is defined as Var(X) Ξ E [X-E(X))2], the covariance is Cov(X, ) EX E(X))Y EY) As a hint, we can prove Cov(aX + b, cY)-ac Cov(X, Y) by ac EX -E(X)HY -E(Y)ac Cov(X, Y) In a similar manner, prove the following properties using the definition of the variance and the covariance: (a) Var(X)-Cov(X,...
Suppose the random variables X, Y and Z are related through the model Y = 2...
Suppose the random variables X, Y and Z are related through the
model
Y = 2 + 2X + Z,
where Z has mean 0 and variance σ2 Z = 16 and X has variance σ2
X = 9. Assume X and Z are independent, the find the covariance of X
and Y and that of Y and Z. Hint: write Cov(X, Y ) = Cov(X, 2+2X+Z)
and use the propositions of covariance from slides of Chapter
4.
Suppose the...
Let X and Y be two random variables such that: Var[X]=4 Cov[X,Y]=2 Compute the following covariance:...
Let X and Y be two random variables such that: Var[X]=4 Cov[X,Y]=2 Compute the following covariance: Cov[3X,X+3Y]
Let X, Y, Z be random variables with these properties: · E[X] = 3 and E[X²]...
Let X, Y, Z be random variables with these properties: · E[X] = 3 and E[X²] = 10 Var(Y) = 5 E[Z] = 2 and E[Z2] = 7 • X and Y are independent E[X2] = 5 Cov(Y,Z) = 2 Find Var(3X+Y – Z).
Let X and Y be two independent Bernoulli( 1/2 ) random variables. Define random variables U...
Let X and Y be two independent Bernoulli( 1/2 ) random variables. Define random variables U and V by U = X + Y and V = | (X - Y) | (abs. value)): (a) Find the joint probability mass function of (U, V ). Hints: note that U and V are taking integer values in {0, 1, 2} and {0, 1}, respectively. (b) Determine the covariance Cov(U, V ): (c) Find Var(U), Var(V ) and determine the correlation coeffcient p(U,...
15. The means, standard deviations, and covariance for random variables X, Y. and Z are given below. x = 3, uy = 5. z = 7 ox= 1, OY = 3, oz = 4 cov(X, Y) = 1, cov (X, Z) = 3, and cov (Y,Z) = -3 T=X-2Y+3 Z var(T) =
Exercise 1 (1). X, Y are random variables (r.v.) and a,b,c,d are values. Complete the formulas using the expectations E(X), E(Y), variances Var(X), Var(Y) and covariance Cov(X, Y) (a) E(aX c) (b) Var(aX + c (d) Var(aX bY c) (e) The covariance between aX +c and bY +d, that is, Cov(aX +c,bY +d) f) The correlation between X, Y that is, Corr(X,Y (g) The correlation between aX +c and bY +d, that is, Corr(aX + c, bY +d)
5. The means, standard deviations, and covariance for random variables X, Y, and Z are given below. Ux= 3, uy = 5, uz = 7 Ox= 1, OY = 3, oz = 4 cov(X, Y) = 1, cov (X, Z) = 3, and cov (Y,Z) = -3 T= X-28 +3 Z var(T) = 16. For a random variable X with an unknown distribution. The mean of X is u = 22 and tting a randomly chosen value of X
5.8.6
otherwise. (a) Find the correlation rx.y (b) Find the covariance Cov(X,Y]. 5.8.6 The random variables X and Y have (b) Use part Cov oint PMF (c) Show tha Var[ (d) Combine Px,y and 5.8.10 Ran the joint PM PN,K (n, k) 0 0 Find (a) The expected values E[X] and EY, pected (b) The variances Var(X] and Var[Y],VarlK], E Find the m
Prove the following properties using the definition of the
variance and the covariance:
Q1. Operations with expectation and covariances Recall that the variance of randon variable X is defined as Var(X) Ξ E [X-E(X))2], the covariance is Cov(X, ) EX E(X))Y EY) As a hint, we can prove Cov(aX + b, cY)-ac Cov(X, Y) by ac EX -E(X)HY -E(Y)ac Cov(X, Y) In a similar manner, prove the following properties using the definition of the variance and the covariance: (a) Var(X)-Cov(X,...
Suppose the random variables X, Y and Z are related through the
model
Y = 2 + 2X + Z,
where Z has mean 0 and variance σ2 Z = 16 and X has variance σ2
X = 9. Assume X and Z are independent, the find the covariance of X
and Y and that of Y and Z. Hint: write Cov(X, Y ) = Cov(X, 2+2X+Z)
and use the propositions of covariance from slides of Chapter
4.
Suppose the...
Let X, Y, Z be random variables with these properties: · E[X] = 3 and E[X²] = 10 Var(Y) = 5 E[Z] = 2 and E[Z2] = 7 • X and Y are independent E[X2] = 5 Cov(Y,Z) = 2 Find Var(3X+Y – Z).
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