If four persons are chosen at random from a group of $3$ men,$2$ women and $4$ children,then the probability that exactly two of them are children is:

Four cards are drawn one by one from a well-shuffled pack of $52$ cards. What is the probability that all four cards belong to the same suit?

If each of the coefficients $a, b, c$ in the equation $ax^2 + bx + c = 0$ is determined by throwing a die,then the probability that the equation will have equal roots is:

What is the probability of drawing two kings from a well-shuffled deck of $52$ cards?

$A$ box contains $10$ red marbles,$20$ blue marbles,and $30$ green marbles. If $5$ marbles are drawn from the box,what is the probability that at least one will be green?

$A$ container contains nine balls: three red,four blue,and two green. If three balls are selected at random from the container without replacement,what is the probability that all three balls are of different colors?