There are $4$ envelopes with addresses and $4$ concerning letters. The probability that letter does not go into concerning proper envelope, is

If $\frac{2}{11}$ is the probability of an event, what is the probability of the event $'$ not $A ^{\prime}$.

A fair coin with $1$ marked on one face and $6$ on the other and a fair die are both tossed. find the probability that the sum of numbers that turn up is $12$.

A die is thrown, find the probability of following events: A number less than $6$ will appear,

Let two fair dices $A$ and $B$ are thrown. Then the probability that number appears on dice $A$ is greater than number appears on dice $B$ is

Two dice are thrown and the sum of the numbers which come up on the dice is noted. Let us consider the following events associated with this experiment

$A:$ $^{\prime}$ the sum is even $^{\prime}$.
$B:$ $^{\prime}$the sum is a multiple of $3$$^{\prime}$
$C:$ $^{\prime}$the sum is less than $4 $$^{\prime}$
$D:$ $^{\prime}$the sum is greater than $11$$^{\prime}$.

Which pairs of these events are mutually exclusive ?