A random variable takes the values 1, 5 and 4 with probabilities 1/2, 1/3 and 1/6 respectively. What is its expected value?
Answer and explanation
Correct answer: D. 2.8
- Step 1: E[X] = Σ x·p = 1/2 + 5/3 + 4/6. Step 2. = 2.8. Answer: 2.8. Why not the others: 3.3 is what you get if you average the values without weights. 10 is what you get if you add the values. 3.8 is what you get if you miscalculate one term.
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