X1 and X2 are independent with same distribution: SD = 5.
Which has greater SD: X1 + X2 or 2X1?
- Acheck_circle
2X1 has SD 10; X1+X2 has SD ≈ 7.07
- B
Both have SD 5
- C
Both have SD 10
- D
X1+X2 has SD 10
Explanation
Var(X1+X2) = 25+25 = 50, SD ≈ 7.07. Var(2X1) = 4*25 = 100, SD = 10.