If Var(X) = 9, what is Var(4X − 7)?
Correct answer: D. 81
- A. 9
- B. 16
- C. 36
- D. 81
Explanation
For a linear transformation, Var(aX + b) = a²Var(X), while the constant b has no effect. Thus Var(4X − 7) = 4² × 9 = 144, so none of the listed options is correct.
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