(A) For independent events:
\[ P(A \cap B) = P(A) \cdot P(B) = 0.5 \cdot 0.4 = 0.2. \](B) Using the formula:
\[ P(A \cup B) = P(A) + P(B) - P(A \cap B). \]Substituting values:
\[ P(A \cup B) = 0.5 + 0.4 - 0.2 = 0.7. \]The probability distribution of the random variable X is given by
| X | 0 | 1 | 2 | 3 |
|---|---|---|---|---|
| P(X) | 0.2 | k | 2k | 2k |
Find the variance of the random variable \(X\).