A discrete probability distribution has P(X = 1) = 0.2, P(X = 2) = 0.5, and P(X = 3) = 0.3. What is the expected value E(X)?
Answer and explanation
Correct answer: D. 2.1
- Step 1: Formula: E(X) = sum x P(X = x). Step 2. Compute terms: 1(0.2) + 2(0.5) + 3(0.3). Step 3. Add: 0.2 + 1.0 + 0.9 = 2.1. Answer: 2.1. Why not the others:* 2.0 is the mode, not expectation; 2.3 and 1.9 result from multiplication errors.
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