Three ships A, B, C sail from England to India. If the odds in favour of their safe arrival are 2:5, 3:7 and 6:11 respectively, then the probability that the exactly two ships arrive safely is

A random variable X has the probability distribution

$X = x$	$1$	$2$	$3$	$4$	$5$	$6$	$7$	$8$
$P(X = x)$	$0.23$	$0.15$	$0.12$	$0.10$	$0.20$	$0.07$	$0.08$	$0.05$

for the events E = {X is a prime number} and F = {X $\leq$ 3}, then P (E$\cup$F)=

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