# Math Help - random variables and variance

1. ## random variables and variance

if we let X be a (continous or discrete) random variable with range
Rx[-a,a]
how can we find Var(X) which is less or equal than a^2??

2. Originally Posted by xixihaha
if we let X be a (continous or discrete) random variable with range
Rx[-a,a]
how can we find Var(X) which is less or equal than a^2??
$Var(X) = E(X^2) - [E(X)]^2$.