Questions: An event X will occur with probability 0.4. The conditional probability that event Y will occur given that X occurs is 0.8. What is the probability that both X and Y will occur? A 0.40 B 0.12 C 0.32 D 0.50 E 0.20

An event X will occur with probability 0.4. The conditional probability that event Y will occur given that X occurs is 0.8.

What is the probability that both X and Y will occur?

A 0.40

B 0.12

C 0.32

D 0.50

E 0.20
Transcript text: An event $X$ will occur with probability 0.4 . The conditional probability that event $Y$ will occur given that $X$ occurs is 0.8 . What is the probability that both $X$ and $Y$ will occur? A 0.40 B $\quad 0.12$ C $\quad 0.32$ D 0.50 E $\quad 0.20$
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Solution

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Solution Steps

Step 1: Identify the given probabilities

We are given:

  • \( P(X) = 0.4 \) (the probability that event \( X \) occurs).
  • \( P(Y|X) = 0.8 \) (the conditional probability that event \( Y \) occurs given that \( X \) occurs).
Step 2: Use the definition of conditional probability

The conditional probability \( P(Y|X) \) is defined as: \[ P(Y|X) = \frac{P(X \cap Y)}{P(X)} \] where \( P(X \cap Y) \) is the probability that both \( X \) and \( Y \) occur.

Step 3: Solve for \( P(X \cap Y) \)

Rearrange the formula to solve for \( P(X \cap Y) \): \[ P(X \cap Y) = P(Y|X) \cdot P(X) \] Substitute the given values: \[ P(X \cap Y) = 0.8 \cdot 0.4 = 0.32 \]

Final Answer

\(\boxed{0.32}\)

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