Math Problem Statement
- The probability distribution table for X and Y is presented below. Y\X 0 1 2 0 0.05 0.1 0.03 1 0.21 0.11 0.19 2 0.08 0.15 0.08 1-a) compute COV(X 2 , Y)
Solution
To compute , we follow these steps:
Step 1: Recall the formula for covariance
The covariance between two random variables and is given by: [ \text{COV}(X^2, Y) = E[X^2 Y] - E[X^2] E[Y] ] We need to compute three things:
- — the expected value of the product of and ,
- — the expected value of ,
- — the expected value of .
Step 2: Calculate
Using the joint probability distribution table, we compute as: We apply the table values.
For :
For :
For :
Now, summing all the terms:
Step 3: Calculate
Now, calculate the expected value of :
For :
For :
For :
Now, summing these values:
Step 4: Calculate
Now, calculate the expected value of :
For :
For :
For :
Now, summing these values:
Step 5: Calculate the covariance
Now, substitute everything into the covariance formula: [ \text{COV}(X^2, Y) = E[X^2 Y] - E[X^2] E[Y] = 1.73 - (1.75 \cdot 0.96) ]
Thus, the covariance is .
Would you like further clarification or details on any step?
Here are 5 related questions for further practice:
- How would you calculate using the same table?
- What is the variance of ?
- How would you find from the same table?
- What is the joint probability distribution function?
- How can you find the marginal distribution of ?
Tip: Covariance is a measure of how two random variables change together. If it's positive, they tend to increase together, and if it's negative, one increases while the other decreases.
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Math Problem Analysis
Mathematical Concepts
Probability
Covariance
Expected Value
Formulas
COV(X^2, Y) = E[X^2 Y] - E[X^2] E[Y]
E[X^2 Y] = Σ_x Σ_y (x^2 ⋅ y ⋅ P(X=x, Y=y))
E[X^2] = Σ_x (x^2 ⋅ P(X=x))
E[Y] = Σ_y (y ⋅ P(Y=y))
Theorems
Law of Expected Value
Covariance Formula
Suitable Grade Level
Grades 11-12
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