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Probability — Maths STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceMathsProbability1 Mark
MCQ
Let $X$ be a discrete random variable. Then the variance of $X$ is :
  • A
    $E(X^2$)
  • B
    $E(X^2) + (E(X))^2$
  • C
    $E(X^2) - (E(X))^2$
  • ✓
    $\sqrt{\text{E}(\text{X}^2)-(\text{E}(\text{X}))^2}$
✓

Answer

Correct option: D.
$\sqrt{\text{E}(\text{X}^2)-(\text{E}(\text{X}))^2}$
Since, the variance of a discrete random variable $X$ is given by :
$\text{Var}(X) = E(X^2) - (E(X))^2$
Hence, the correct alternative is option $(c).$

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