$A$ 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?

Two persons $A$ and $B$ have respectively $n + 1$ and $n$ coins which they toss simultaneously. Then the probability that $A$ will have more heads than $B$ is

Three boys and two girls stand in a queue. The probability that the number of boys ahead of every girl is at least one more than the number of girls ahead of her is:

$A$ box contains $2$ black,$4$ white and $3$ red balls. One ball is drawn at random from the box and kept aside. From the remaining balls in the box,another ball is drawn at random and kept aside the first. This process is repeated until all the balls are drawn from the box. The probability that the balls drawn are in the sequence of $2$ black,$4$ white and $3$ red is

$\omega$ is a complex cube root of unity. When an unbiased die is thrown $3$ times,if $\beta_1, \beta_2, \beta_3$ are the numbers appeared on the die,then the probability that $\beta_1, \beta_2$ and $\beta_3$ satisfy $\omega^{\beta_1}+\omega^{\beta_2}=-\omega^{\beta_3}$ is

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