Question

For a random variable $X$. If $E\left(X\right)=5$ and $V\left(X\right)=6$, then $E\left(X^2\right)$ is equal to

• A. $19$
• B. $31$
• C. $61$
• D. $11$

Answer 1

The correct option is B $31$

As we know that,

$V\left(X\right)=E\left(X^2\right)-{\left(E\left(X\right)\right)}^2$

$\therefore 6=E\left(X^2\right)-5^2$

$\Rightarrow E\left(X^2\right)=6+25=31$