A discrete random variable X takes the values 1, 2, and 4 with probabilities 0.2, 0.5, and 0.3, respectively. What is E(X)?
Correct answer: B. 2.40
- A. 2.10
- B. 2.40
- C. 2.70
- D. 3.00
Explanation
The expected value is found by multiplying each value by its probability and adding the results: (1 × 0.2) + (2 × 0.5) + (4 × 0.3) = 2.4. It is a probability-weighted average, not the simple average of the values.
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