Math Problem Statement

Let A and B be events with P(A) = 0.6, P(B) = 0.4, and P(A or B) = 0.8. (a) Compute P(A and B). (b) Are A and B mutually exclusive? Explain. (c) Are A and B independent? Explain.

Solution

Let's solve the given problems step-by-step.

(a) Compute P(A and B)P(A \text{ and } B).

We use the formula for the union of two events:

P(AB)=P(A)+P(B)P(AB)P(A \cup B) = P(A) + P(B) - P(A \cap B)

Plugging in the values provided:

0.8=0.6+0.4P(AB)0.8 = 0.6 + 0.4 - P(A \cap B)

Solving for P(AB)P(A \cap B):

P(AB)=0.6+0.40.8=0.2P(A \cap B) = 0.6 + 0.4 - 0.8 = 0.2

So, P(A and B)=0.2P(A \text{ and } B) = 0.2.

(b) Are AA and BB mutually exclusive?

Two events are mutually exclusive if they cannot occur at the same time, i.e., P(AB)=0P(A \cap B) = 0.

Since P(AB)=0.20P(A \cap B) = 0.2 \neq 0, AA and BB are not mutually exclusive.

(c) Are AA and BB independent?

Two events AA and BB are independent if P(AB)=P(A)×P(B)P(A \cap B) = P(A) \times P(B).

Calculating P(A)×P(B)P(A) \times P(B):

P(A)×P(B)=0.6×0.4=0.24P(A) \times P(B) = 0.6 \times 0.4 = 0.24

Since P(AB)=0.20.24P(A \cap B) = 0.2 \neq 0.24, AA and BB are not independent.


Would you like more details or have any specific questions on these calculations?

Related Questions:

  1. How do you calculate the probability of the complement of AA and BB?
  2. What is the probability of either AA or BB occurring, given their independence?
  3. How would the result change if P(A)P(A) was greater than 1?
  4. What does it mean for events to be independent in real-life scenarios?
  5. How do you verify mutual exclusivity if the events are part of a complex system?

Tip: Always remember that mutually exclusive events cannot happen simultaneously, while independent events have no effect on each other's occurrence.

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Math Problem Analysis

Mathematical Concepts

Probability
Mutually Exclusive Events
Independent Events

Formulas

P(A ∪ B) = P(A) + P(B) - P(A ∩ B)
Mutually Exclusive: P(A ∩ B) = 0
Independent Events: P(A ∩ B) = P(A) × P(B)

Theorems

Union of Events Theorem
Mutual Exclusivity Theorem
Independence Theorem

Suitable Grade Level

Grades 10-12