$4$ coins are tossed once. Find the probability of getting exactly $3$ tails.

$A$ dice is thrown twice. The probability of getting $4, 5$ or $6$ in the first throw and $1, 2, 3$ or $4$ in the second throw is

$A$ husband and wife appear in an interview for $2$ vacancies in the same post. The probability of the husband's selection is $1/7$ and that of the wife's is $1/5$. What is the probability that at least one of them will be selected?

$A$ drawer contains $50$ bolts and $150$ nuts. Half of the bolts and half of the nuts are rusted. If $1$ item is chosen at random,what is the probability that it is rusted or is a bolt?

$A$ letter is known to have come either from $LONDON$ or $CLIFTON$; on the postmark only the two consecutive letters $ON$ are legible. The probability that it came from $LONDON$ is

If a coin is tossed $n$ times,then the probability that the head comes up an odd number of times is: