Properties of expectation and variance

Properties of expectation and variance

IB Year 5 | Grade 11

Prove that for all random variable \(X\), and any real numbers \(a\), \(b\),

\[\mathrm{E}(aX + b) = a\mathrm{E}(X) + b\]

and

\[\mathrm{Var}(aX + b) = a^2\mathrm{Var}(X)\]

Solution:

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Answer:Provided the required moments are finite, \(\mathrm E(aX+b)=a\mathrm E(X)+b\) and \(\operatorname{Var}(aX+b)=a^2\operatorname{Var}(X)\).

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