$E(X)=7$ and $Var(X)=5.83333$,
Here is my working:
Given that $E(X)=7, E(X^3)=343$??, hence $E(4X^3+5)= 4$, $E(X^3)+5 = 1377$
and $SD(X) = 2.4152$, $SD(X^3)=14.09$ hence $SD(4X^3 +5) = 4SD(X^3) = 56.35$
Is this the correct approach?
2026-03-29 14:03:03.1774792983
Given that random variable $X$ is the sum of two independent fair dice, what is $E(4X^3 + 5)$ and $SD(4X^3 +5)$?
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