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Compute the indicated quantity. $$ P(A \mid B)=.2, P(B)=.4 \text { . Find } P(A \cap B) \text { . } $$

Short Answer

Expert verified
The probability of the intersection of \(A\) and \(B\), denoted as \(P(A \cap B)\), is 0.08.

Step by step solution

01

Understanding the formula for conditional probability

The conditional probability of an event \(A\) given that event \(B\) occurs is given by the formula: \[P(A \mid B) = \frac{P(A \cap B)}{P(B)}\] In our exercise, we are given \(P(A \mid B)\) and \(P(B)\), and we need to find \(P(A \cap B)\).
02

Plug in the given values

Using the formula for conditional probability, we have: \[ 0.2 = \frac{P(A \cap B)}{0.4} \]
03

Solve for the intersection probability P(A ∩ B)

Now we just need to solve this equation for \(P(A \cap B)\). To do this, multiply both sides of the equation by the probability of \(B\), which is 0.4: \[ 0.2 \times 0.4 = P(A \cap B) \]
04

Compute the result

Multiply 0.2 by 0.4 to find the probability of the intersection of events \(A\) and \(B\): \[ 0.08 = P(A \cap B) \] Therefore, the probability of the intersection of \(A\) and \(B\), denoted as \(P(A \cap B)\), is 0.08.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Intersection of Events
In probability theory, an intersection refers to the occurrence of two events at the same time. We denote this as \(A \cap B\), where \(A\) and \(B\) are the events in question. The concept of intersection is crucial when computing probabilities for events that depend on each other.
Understanding intersections helps us understand the likelihood of two or more conditions being true simultaneously. In the context of our exercise, the intersection \(P(A \cap B)\) represents the probability that both event \(A\) and event \(B\) occur together. This is calculated using the relationship given by conditional probability, where one event occurs given the occurrence of another event. Through this method, we are able to determine overlaps in real-world scenarios, like the probability of rain and a sunny day on a particular afternoon.
Recognizing intersections can simplify complex problems:
  • It focuses on simultaneous occurrences.
  • Intersected events are widely applicable in statistics and real-life experiments.
  • Understanding intersections leads to better decision-making under uncertainty.
Probability Theory
Probability theory is the mathematical framework that quantifies uncertainty. It is the study of randomness and is foundational to statistics. In essence, probability helps predict the likelihood of various outcomes in a given experiment or situation. This branch of mathematics defines events and outcomes, assigning each a probability value that ranges between 0 and 1.
Our exercise focuses on conditional probability, a subset of probability theory. Conditional probability is the probability of an event \(A\), given that another event \(B\) has occurred. It refines our understanding of events as it leverages information about dependencies between them.
Key points to remember in probability theory include:
  • It is applicable to fields such as finance, insurance, and everyday decision-making.
  • It provides tools to calculate chances of happening, using events and sample spaces.
  • Understanding concepts like independent, mutually exclusive, and dependent events improves predictive analysis.
Mathematical Calculation
The process of calculating probabilities involves both understanding formulas and legitimate computation steps. In our exercise, we used the formula for conditional probability:\[P(A \mid B) = \frac{P(A \cap B)}{P(B)}\]This formula essentially helps in calculating the probability of the intersection of two events by using the known probabilities of each event independently and one event given another.
The step-by-step breakdown makes sure that anyone, irrespective of mathematical fluency, can follow and compute the probabilities. It involves:
  • Identifying the correct formula and substituting the known values.
  • Using multiplication or division to isolate and find unknown values.
  • Arriving at a concise result, here \(P(A \cap B) = 0.08\), through logical and straightforward steps.
Understanding mathematical calculations like this builds a stronger grasp over practical problems, ensuring that when faced with similar challenges, the approach and interpretation remain clear and effective.

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