Math Problem Statement

Suppose two random variables X and Y have the following probability distributions:

x 0 1 2 y 8 2 6 10 p(x) 0.1 0.3 0.6 p(y) 0.4 0.1 0.2 0.3

Calculate E[X] and E[Y] .

Solution

To calculate the expected values E[X]E[X] and E[Y]E[Y], we will use the formula for expected value:

E[X]=xp(x)E[X] = \sum x \cdot p(x) E[Y]=yp(y)E[Y] = \sum y \cdot p(y)

Calculating E[X]E[X]:

From the given values of xx and p(x)p(x):

  • x=0,p(x)=0.1x = 0, p(x) = 0.1
  • x=1,p(x)=0.3x = 1, p(x) = 0.3
  • x=2,p(x)=0.6x = 2, p(x) = 0.6

Now, using the formula for expected value:

E[X]=(00.1)+(10.3)+(20.6)E[X] = (0 \cdot 0.1) + (1 \cdot 0.3) + (2 \cdot 0.6) E[X]=0+0.3+1.2=1.5E[X] = 0 + 0.3 + 1.2 = 1.5

Calculating E[Y]E[Y]:

From the given values of yy and p(y)p(y):

  • y=8,p(y)=0.4y = 8, p(y) = 0.4
  • y=2,p(y)=0.1y = 2, p(y) = 0.1
  • y=6,p(y)=0.2y = 6, p(y) = 0.2
  • y=10,p(y)=0.3y = 10, p(y) = 0.3

Now, using the formula for expected value:

E[Y]=(80.4)+(20.1)+(60.2)+(100.3)E[Y] = (8 \cdot 0.4) + (2 \cdot 0.1) + (6 \cdot 0.2) + (10 \cdot 0.3) E[Y]=3.2+0.2+1.2+3=7.6E[Y] = 3.2 + 0.2 + 1.2 + 3 = 7.6

Final Answer:

  • E[X]=1.5E[X] = 1.5
  • E[Y]=7.6E[Y] = 7.6

Would you like to explore more about these calculations, or do you have any specific questions about expected values? Here are some related questions to consider:

  1. How does the expected value relate to the variance of a random variable?
  2. What would happen to E[X]E[X] if the probability distribution for XX changed?
  3. How do you calculate the expected value of the sum of two random variables?
  4. What is the difference between discrete and continuous random variables when calculating expected value?
  5. Can you compute the covariance between XX and YY from their distributions?

Tip: To better understand expected values, think of it as the "weighted average" of all possible outcomes of a random variable, where the probabilities are the weights.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Probability Theory
Expected Value
Random Variables

Formulas

E[X] = Σ x * p(x)
E[Y] = Σ y * p(y)

Theorems

Expected Value Theorem

Suitable Grade Level

Grades 10-12