What is the probability that when one die is thrown,the number appearing on top is even?

An $URN$ contains $6$ blue,$4$ red,$3$ green and $2$ yellow marbles. If four marbles are picked at random,what is the probability that one is yellow,two are red and one is blue?

$A$ single die is tossed. What is the probability of a $2$ turning up?

An urn contains $25$ balls numbered $1$ to $25$. Suppose an odd number is considered a 'success'. If $2$ balls are drawn from the urn with replacement,find the probability of getting at most $2$ successes.

If the probabilities of a boy and a girl being born are the same,then in a $4$ children family,the probability of having at least one girl is:

$n$ cadets have to stand in a row. If all possible permutations are equally likely,then the probability that two particular cadets stand side by side,is