From $21$ tickets numbered $1, 2, 3, \ldots, 21$,one ticket is drawn at random. Find the probability that the ticket drawn has a number divisible by $3$.

$A$ bag contains $4$ white,$5$ red,and $6$ green balls. Three balls are picked up randomly. The probability that a white,a red,and a green ball is drawn is

In a single throw of $3$ dice,find the probability of getting a total of at most $5$.

Two cards are drawn from a well-shuffled ordinary deck of $52$ cards. What is the probability that they are both aces if the first card is not replaced?

$A$ determinant is chosen at random from the set of all determinants of order $2$ with elements $0$ or $1$ only. The probability that the value of the determinant chosen is positive is:

$A$ box contains $6$ white and $8$ red balls. Two balls are drawn at random in succession. What is the probability that one of them is white and the other red?