NDA 2026 · PYQ · Statistics / Variance Transformation · easy
If the random variable X has mean 3 and standard deviation 5, then what is the variance of the random variable Y = 2X - 5?
- A.15
- B.40
- C.45
- D.100✓ Correct
For Y = aX + b, Var(Y) = a²·Var(X). Here a = 2, Var(X) = 5² = 25. So Var(Y) = 4 × 25 = 100.
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