A fair six-sided die is rolled once. The variance of the number obtained on the top face is:
A fair six-sided die is rolled once. The variance of the number obtained on the top face is:
- A. 35/12
- B. 3.5
- C. 91/6
- D. 49/4
Answer: A) 35/12
Explanation: E(X) = 3.5. E(X²) = (1²+2²+3²+4²+5²+6²)/6 = 91/6. Var(X) = 91/6 − (7/2)² = 91/6 − 49/4 = 35/12.
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