There are $n$ letters and $n$ addressed envelopes. The probability that all the letters are not kept in the right envelope, is

A coin is tossed and a dice is rolled. The probability that the coin shows the head and the dice shows $6$ is

Three coins are tossed once. Find the probability of getting atleast $2$ heads.

There are $10$ pairs of shoes in a cupboard from which $4$ shoes are picked at random. The probability that there is at least one pair, is

Two dice are thrown. The events $A, B$ and $C$ are as follows:

$A:$ getting an even number on the first die.

$B:$ getting an odd number on the first die.

$C:$ getting the sum of the numbers on the dice $\leq 5$

Describe the events  $A$ but not $C$

A problem of mathematics is given to three students whose chances of solving the problem are $\frac{{1}}{{3}} , \frac{{1}}{{4}}$ and $\frac{{1}}{{5}}$ respectively. The probability that the question will be solved is