The probability distribution of a random variable X is given by

$X = x$	$1$	$2$	$3$	$4$
$P(X = x)$	$k$	$2k$	$3k$	$4k$

Then the c.d.f. of X is given by

Two dice are thrown successively 4 times and getting a doublet is called a success. The probability of getting at least 1 success is

If 6 boys and 3 girls are to be seated in a row for a photograph, then the probability that the end seats are occupied by the girls and no two girls are side by side is

For the following probability distribution, the standard deviation of the random variable X is

X	2	3	4
p(X=$x$)	0.2	0.5	0.3