Multiple choice

If E denotes expectation, then the variance of a random variable X is given by

  1. E [x2] – E2 [x]

  2. E [x2] + E2 [x]

  3. E [x2]

  4. E2 [x]

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A Correct answer
Explanation

The variance of a random variable $x$ is given by $E[X^2] - D^Q[X]$