Answer: 4.
- A 4
- B 10
- C 9
- D 16
Correct answer: A. 4
Explanation: Variance formula: Var(X) = E[X²] − (E[X])². Substituting: Var(X) = 13 − 3² = 13 − 9 = 4. Standard deviation SD = √4 = 2. This is the shortcut form avoiding direct computation of Σ(xᵢ−μ)²p(xᵢ).
Venn diagram of the universal set U with events A and B, showing the intersection (A and B), the parts unique to each event, and the complement region outside both.
Concept context
Chance, events, conditional probability, and Bayes theorem