If $P(X=x)=c\left(\frac{2}{3}\right)^x$ for $x=1, 2, 3, 4, \ldots$ is a probability distribution function of a random variable $X$,then the value of $c$ is

If the function $f$ defined by $f(x) = \begin{cases} K(x-x^2) & \text{if } 0 < x < 1 \\ 0 & \text{otherwise} \end{cases}$ is the probability density function (p.d.f.) of a random variable $X$,then the value of $P(X < \frac{1}{2})$ is

Two numbers are selected at random from the first six positive integers. If $X$ denotes the larger of the two numbers,then $\operatorname{Var}(X) = $

The probability distribution of a random variable $X$ is as follows. Then the mean of $X$ is

$X = x_{i}$	$-2$	$-1$	$0$	$1$	$2$
$P(X = x_{i})$	$k^2 / 3$	$k^2$	$2k^2 / 3$	$k / 2$	$k / 2$

Three rotten apples are mixed accidentally with seven good apples and four apples are drawn one by one without replacement. Let the random variable $X$ denote the number of rotten apples. If $\mu$ and $\sigma^2$ represent the mean and variance of $X$,respectively,then $10(\mu^2 + \sigma^2)$ is equal to

Two numbers are selected at random,without replacement from the first $6$ positive integers. Let $X$ denote the larger of the two numbers. Then $E(X) = $