Math Problem Statement

Rework problem 2 from section 3.1 of your text, involving events A and B in a sample space S. Assume that P(A) = 0.35, P(B) = 0.5, and P(A' ∩ B) = 0.3. Find the following probabilities: P(B' ∩ A), P(A ∩ B), P(A' ∩ B').

Solution

Here’s the breakdown of the problem based on the provided image:

We are tasked to find the following probabilities:

  1. P(BA)P(B' \cap A)
  2. P(AB)P(A \cap B)
  3. P(AB)P(A' \cap B')

Given Information:

  • P(A)=0.35P(A) = 0.35
  • P(B)=0.5P(B) = 0.5
  • P(AB)=0.3P(A' \cap B) = 0.3

Solution Steps:

1. P(BA)P(B' \cap A):

Using the complement rule, we know: P(BA)=P(A)P(AB).P(B' \cap A) = P(A) - P(A \cap B).

To solve this, we need P(AB)P(A \cap B).

2. P(AB)P(A \cap B):

From the given data, we can calculate: P(AB)=P(A)P(AB),P(A \cap B) = P(A) - P(A' \cap B), since P(A)=P(AB)+P(AB)P(A) = P(A \cap B) + P(A' \cap B).

Substitute: P(AB)=0.350.3=0.05.P(A \cap B) = 0.35 - 0.3 = 0.05.

3. P(BA)P(B' \cap A) (continued):

Now substitute P(AB)P(A \cap B) into the equation: P(BA)=P(A)P(AB)=0.350.05=0.3.P(B' \cap A) = P(A) - P(A \cap B) = 0.35 - 0.05 = 0.3.

4. P(AB)P(A' \cap B'):

Using the inclusion-exclusion principle, we know: P(AB)=1P(AB).P(A' \cap B') = 1 - P(A \cup B).

Also, P(AB)P(A \cup B) can be written as: P(AB)=P(A)+P(B)P(AB).P(A \cup B) = P(A) + P(B) - P(A \cap B).

Substitute values: P(AB)=0.35+0.50.05=0.8.P(A \cup B) = 0.35 + 0.5 - 0.05 = 0.8.

Thus: P(AB)=10.8=0.2.P(A' \cap B') = 1 - 0.8 = 0.2.

Final Results:

  1. P(BA)=0.3P(B' \cap A) = 0.3
  2. P(AB)=0.05P(A \cap B) = 0.05
  3. P(AB)=0.2P(A' \cap B') = 0.2

Would you like a detailed explanation of any step?

Here are 5 related questions to further your understanding:

  1. What is the complement rule, and how is it applied in probability problems?
  2. Can you derive P(AB)P(A' \cap B') using other methods?
  3. How does the inclusion-exclusion principle work in probability?
  4. What other relationships exist between P(AB)P(A \cap B) and P(AB)P(A \cup B)?
  5. How can these concepts be extended to more than two events?

Tip: Drawing a Venn diagram can help visualize intersections and complements in probability problems!

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Math Problem Analysis

Mathematical Concepts

Probability
Set Theory
Complement Rule
Inclusion-Exclusion Principle

Formulas

P(B' ∩ A) = P(A) - P(A ∩ B)
P(A ∩ B) = P(A) - P(A' ∩ B)
P(A' ∩ B') = 1 - P(A ∪ B)
P(A ∪ B) = P(A) + P(B) - P(A ∩ B)

Theorems

Complement Rule
Inclusion-Exclusion Principle

Suitable Grade Level

Grades 10-12