Math Problem Statement

Convert the variables X1, X2, X3 to new random variables Y1, Y2, Y3 using a given transformation matrix T. Find the covariance matrix of the new random variables.

Solution

The problem involves transforming a set of random variables X1,X2,X3X_1, X_2, X_3 (with given covariance matrix CXC_X) into a new set of random variables Y1,Y2,Y3Y_1, Y_2, Y_3 using a transformation matrix TT. You are asked to find the covariance matrix of the new random variables.

Given:

  1. Covariance matrix CXC_X: 3.0 & 1.8 & 1.1 \\ 1.8 & 3.0 & 1.8 \\ 1.1 & 1.8 & 1.1 \end{bmatrix}$$
  2. Transformation matrix TT: 4 & -1 & -2 \\ 2 & 2 & 1 \\ -3 & -1 & 3 \end{bmatrix}$$

To Find:

The covariance matrix CYC_Y of the new random variables Y1,Y2,Y3Y_1, Y_2, Y_3, where: CY=TCXTTC_Y = T C_X T^T where TTT^T is the transpose of the transformation matrix TT.

I'll now calculate the new covariance matrix CYC_Y.The covariance matrix CYC_Y of the new random variables Y1,Y2,Y3Y_1, Y_2, Y_3 is:

30.6 & 17.6 & -23.4 \\ 17.6 & 51.1 & -22.8 \\ -23.4 & -22.8 & 20.1 \end{bmatrix}$$ This matrix represents the covariances of the transformed variables. Do you want further details on how this result was derived or have any questions? Here are 5 related questions for further understanding: 1. How is a covariance matrix interpreted in the context of random variables? 2. Why do we use transformation matrices on covariance matrices? 3. How would the covariance matrix change if the transformation matrix $$T$$ were different? 4. What does a negative value in the covariance matrix imply about the relationship between two variables? 5. Can you generalize this approach to higher dimensions? **Tip**: To ensure matrix multiplication is valid, remember that the number of columns in the first matrix must equal the number of rows in the second.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Covariance Matrix
Matrix Transformations

Formulas

C_Y = T * C_X * T^T

Theorems

Matrix Multiplication
Covariance Matrix Transformation

Suitable Grade Level

Undergraduate