For a probability distribution if $E(X^2)=0.80 $ and $E(X)=0.40 $, then then its standard deviation is ________ .
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 0.80
for any random variable X, the variance is given by -
$σ^2=E(X)^2-[E(X)]^2$
$=0.80-(0.40)^2$
$=0.80-0.16=0.64$
$σ$, standard deviation = $\sqrt{0.64}=0.8$