Moderate
If a and b are two constants, then Var(a+bX) is_______________?
Correct answer: D. b2Var(X)
- A. a±bVar(X)
- B. Var(a)±Var(X)
- C. ±bVar(X)
- D. b2Var(X)
- E. (a±b)Var(X)
Explanation
Adding the constant a shifts every value but does not change spread, while multiplying by b multiplies variance by b². Hence Var(a+bX) = b²Var(X).
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