A random variable $X$ has the following probability distribution:

$X=x$	$0$	$1$	$3$	$5$
$P(X=x)$	$0·2$	$0·5$	$0·2$	$0·1$

Then, the variance of $X$ is

Then, the value of $a$ is

The $\mathrm{p}.\mathrm{d}.\mathrm{f}.$ of a random variable $X$ is given by $f\left(x\right)=\left\{\begin{array}{ll}kx,& 0<x<2\\ 0,& \text{otherwise}\end{array}\right.$, then $k=$

Then, the variance of this distribution is

The probability distribution of a random variable $X$ is given below:

Then its mean is

The cumulative distribution function of a discrete random variable $X$ is

Then, $P(1<X<5)=$

The following table represents a probability distribution for a random variable $X$ :

Then, the value of $k$ is