Math Problem Statement

Lad A og B være to hændelser i et udfaldsrum U. Benyt multiplikationsloven til at udfylde følgende skema.

Solution

The problem asks you to complete the table using the multiplication rule for probabilities, which is:

P(AB)=P(A)P(BA)P(A \cap B) = P(A) \cdot P(B|A) or equivalently, P(AB)=P(B)P(AB)P(A \cap B) = P(B) \cdot P(A|B)

Let me fill in the missing values based on the given data and the multiplication rule.

First row:

  • P(A)=0.8P(A) = 0.8, P(B)=0.5P(B) = 0.5, and P(AB)=0.4P(A|B) = 0.4
    • P(AB)=P(B)P(AB)=0.50.4=0.2P(A \cap B) = P(B) \cdot P(A|B) = 0.5 \cdot 0.4 = 0.2
    • P(BA)=P(AB)P(A)=0.20.8=0.25P(B|A) = \frac{P(A \cap B)}{P(A)} = \frac{0.2}{0.8} = 0.25

Second row:

  • P(A)=0.5P(A) = 0.5, P(B)=0.4P(B) = 0.4, and P(BA)=0.2P(B|A) = 0.2
    • P(AB)=P(A)P(BA)=0.50.2=0.1P(A \cap B) = P(A) \cdot P(B|A) = 0.5 \cdot 0.2 = 0.1
    • P(AB)=P(AB)P(B)=0.10.4=0.25P(A|B) = \frac{P(A \cap B)}{P(B)} = \frac{0.1}{0.4} = 0.25

Third row:

  • P(A)=0.8P(A) = 0.8, P(AB)=0.5P(A \cap B) = 0.5, and P(BA)=0.25P(B|A) = 0.25
    • P(B)=P(AB)P(AB)=0.50.25=2P(B) = \frac{P(A \cap B)}{P(A|B)} = \frac{0.5}{0.25} = 2 → Check data (wrong value?)

Fourth row:

  • P(A)=0.6P(A) = 0.6, P(B)=0.2P(B) = 0.2, and P(AB)=0.5P(A|B) = 0.5
    • P(AB)=P(B)P(AB)=0.20.5=0.1P(A \cap B) = P(B) \cdot P(A|B) = 0.2 \cdot 0.5 = 0.1
    • P(BA)=P(AB)P(A)=0.10.60.17P(B|A) = \frac{P(A \cap B)}{P(A)} = \frac{0.1}{0.6} \approx 0.17

Fifth row:

  • P(A)=0.4P(A) = 0.4, P(B)=0.5P(B) = 0.5, and P(AB)=0.1P(A \cap B) = 0.1
    • P(AB)=P(AB)P(B)=0.10.5=0.2P(A|B) = \frac{P(A \cap B)}{P(B)} = \frac{0.1}{0.5} = 0.2
    • P(BA)=P(AB)P(A)=0.10.4=0.25P(B|A) = \frac{P(A \cap B)}{P(A)} = \frac{0.1}{0.4} = 0.25

Sixth row:

  • P(A)=0.4P(A) = 0.4, P(B)=0.4P(B) = 0.4, and P(AB)=0.6P(A|B) = 0.6
    • P(AB)=P(B)P(AB)=0.40.6=0.24P(A \cap B) = P(B) \cdot P(A|B) = 0.4 \cdot 0.6 = 0.24
    • P(BA)=P(AB)P(A)=0.240.4=0.6P(B|A) = \frac{P(A \cap B)}{P(A)} = \frac{0.24}{0.4} = 0.6

Let me know if you want further clarifications or details.

Related Questions:

  1. What is the significance of P(AB)P(A \cap B) in probability theory?
  2. How is the conditional probability P(BA)P(B|A) calculated?
  3. Can P(AB)P(A|B) ever be greater than P(A)P(A)?
  4. What happens when P(AB)=0P(A \cap B) = 0? What does this imply?
  5. How would you interpret the multiplication rule in terms of independent events?

Tip:

Always check the consistency of the data in probability problems, as incorrect inputs can lead to contradictions in the results.

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Math Problem Analysis

Mathematical Concepts

Probability Theory
Conditional Probability
Multiplication Rule

Formulas

P(A ∩ B) = P(A) * P(B|A)
P(A ∩ B) = P(B) * P(A|B)
P(A|B) = P(A ∩ B) / P(B)
P(B|A) = P(A ∩ B) / P(A)

Theorems

Multiplication Rule for Probability

Suitable Grade Level

Grades 9-12