Math Problem Statement

Soit (X,Y) un couple de variables aléatoires suivant la loi de probabilité donnée par le tableau ci-dessous: On a : P(X=0 | Y=1) = ?

Solution

The image contains a probability table for a pair of random variables XX and YY, along with the question to find P(X=0Y=1)P(X = 0 \mid Y = 1), the conditional probability.

To solve for P(X=0Y=1)P(X = 0 \mid Y = 1), we use the following formula for conditional probability:

P(X=0Y=1)=P(X=0,Y=1)P(Y=1)P(X = 0 \mid Y = 1) = \frac{P(X = 0, Y = 1)}{P(Y = 1)}

Step-by-step approach:

  1. Find P(X=0,Y=1)P(X = 0, Y = 1): From the table, the probability of X=0X = 0 and Y=1Y = 1 is 10/100 (or 0.10).

  2. Find P(Y=1)P(Y = 1): We sum all probabilities where Y=1Y = 1. From the table:

    • For Y=1Y = 1, the probabilities for X=1,0,1X = -1, 0, 1 are: 10100+10100+8100=28100=0.28\frac{10}{100} + \frac{10}{100} + \frac{8}{100} = \frac{28}{100} = 0.28
  3. Apply the formula: P(X=0Y=1)=0.100.280.3571P(X = 0 \mid Y = 1) = \frac{0.10}{0.28} \approx 0.3571

So, the conditional probability P(X=0Y=1)P(X = 0 \mid Y = 1) is approximately 0.36 (rounded to two decimal places).

Let me know if you need more details or clarification!

Here are some related questions to help further understanding:

  1. How do you calculate the joint probability for two variables?
  2. What is the difference between marginal and conditional probability?
  3. Can you find the probability distribution of XX and YY?
  4. How do you calculate P(Y=1)P(Y = 1) using the marginal probability?
  5. What would be the result if P(X=1Y=0)P(X = -1 \mid Y = 0) were asked?

Tip: When working with conditional probability, remember the formula P(AB)=P(AB)P(B)P(A \mid B) = \frac{P(A \cap B)}{P(B)} and make sure the events in the numerator and denominator correspond correctly!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Probability Theory
Conditional Probability
Joint Probability

Formulas

P(A | B) = P(A ∩ B) / P(B)

Theorems

Bayes' Theorem

Suitable Grade Level

Grades 10-12