Tickets numbered $1$ to $20$ are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of $3$ or $5$?

For two events $A$ and $B$,if $P(A) = P(A|B) = 1/4$ and $P(B|A) = 1/2$,then

If $A$ is a sure event,then the value of $P(A^c)$ is

The probability of India winning a test match against West Indies is $\frac{1}{2}$. Assuming independence from match to match,the probability that in a $5$ match series India's second win occurs at the third test,is

In a single throw of $3$ dice,find the probability of getting a total of $17$ or $18$.

$A$ bag contains $4$ white balls and $2$ black balls. Another bag contains $3$ white balls and $5$ black balls. If one ball is drawn from each bag,then the probability that both the balls are black,is