Math Problem Statement

Determine the following probabilities: P(X <= 2), P(X > -2), P(-1 <= X <= 1), P(X < -1).

Solution

To solve the given problem based on the image:

We are given a probability distribution with the random variable XX taking values 2,1,0,1,2-2, -1, 0, 1, 2 with associated probabilities f(x)f(x) as follows:

X=2,1,0,1,2X = -2, -1, 0, 1, 2 f(X)=0.125,0.25,0.25,0.25,0.125f(X) = 0.125, 0.25, 0.25, 0.25, 0.125

Now, let's address each probability question:

  1. P(X2)P(X \leq 2): Since 2 is the maximum value of XX, P(X2)P(X \leq 2) includes all probabilities, so:

    P(X2)=0.125+0.25+0.25+0.25+0.125=1P(X \leq 2) = 0.125 + 0.25 + 0.25 + 0.25 + 0.125 = 1 Thus, P(X2)=1P(X \leq 2) = 1.

  2. P(X>2)P(X > -2): This excludes X=2X = -2, so:

    P(X>2)=P(X=1)+P(X=0)+P(X=1)+P(X=2)P(X > -2) = P(X = -1) + P(X = 0) + P(X = 1) + P(X = 2) P(X>2)=0.25+0.25+0.25+0.125=0.875P(X > -2) = 0.25 + 0.25 + 0.25 + 0.125 = 0.875

  3. P(1X1)P(-1 \leq X \leq 1): This includes X=1,0,1X = -1, 0, 1, so:

    P(1X1)=P(X=1)+P(X=0)+P(X=1)P(-1 \leq X \leq 1) = P(X = -1) + P(X = 0) + P(X = 1) P(1X1)=0.25+0.25+0.25=0.75P(-1 \leq X \leq 1) = 0.25 + 0.25 + 0.25 = 0.75

  4. P(X<1)P(X < -1): This only includes X=2X = -2, so:

    P(X<1)=P(X=2)=0.125P(X < -1) = P(X = -2) = 0.125

Summary:

  • P(X2)=1P(X \leq 2) = 1
  • P(X>2)=0.875P(X > -2) = 0.875
  • P(1X1)=0.75P(-1 \leq X \leq 1) = 0.75
  • P(X<1)=0.125P(X < -1) = 0.125

Would you like more details or explanations for any of these steps?

Here are some related questions you might find useful:

  1. What is the expected value E(X)E(X) of this probability distribution?
  2. How do we calculate the variance of XX?
  3. What is the cumulative distribution function (CDF) of XX?
  4. How do you find P(0X2)P(0 \leq X \leq 2)?
  5. How would you graph this probability mass function?

Tip: The sum of all probabilities in any discrete probability distribution should always equal 1. This is a good way to check the consistency of a distribution.

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Math Problem Analysis

Mathematical Concepts

Probability
Discrete Probability Distribution

Formulas

P(X <= x) = Sum of probabilities for X <= x
P(a <= X <= b) = Sum of probabilities for a <= X <= b

Theorems

Total Probability Theorem

Suitable Grade Level

High School or College-level Statistics