If three integers are selected at random from the first $20$ integers,what is the probability that their product is even?

Three numbers are chosen from $1$ to $30$. The probability that they are not three consecutive numbers is

Three numbers are chosen at random without replacement from $\{1, 2, \ldots, 10\}$. The probability that the minimum of the chosen numbers is $3$ or their maximum is $7$ is:

Two friends $A$ and $B$ have an equal number of daughters. There are three cinema tickets which are to be distributed among the daughters of $A$ and $B$. The probability that all the tickets go to the daughters of $A$ is $1/20$. The number of daughters each of them has is:

Two digits are selected randomly from the set $\{1, 2, 3, 4, 5, 6, 7, 8\}$ without replacement one by one. The probability that the minimum of the two digits is less than $5$ is

Three squares of a chessboard are chosen at random. The probability that two are of one colour and one is of another colour is: