$A$ die is rolled,find the probability that an even number is obtained.

Find the probability that a two-digit number formed by the digits $1, 2, 3, 4, 5$ is divisible by $4$ (repetition of digits is allowed).

$A$ jar contains $3$ red marbles,$7$ green marbles and $10$ white marbles. If a marble is drawn from the jar at random,what is the probability that this marble is white?

Two dice are thrown. What is the probability that the sum of the numbers appearing on the two dice is $11$,given that $5$ appears on the first die?

Three dice are thrown. Find the chance of getting a sum of $16$.

$A$ mapping is selected at random from the set of all the mappings of the set $A = \{1, 2, ..., n\}$ into itself. The probability that the mapping selected is an injection is