If a coin is tossed $n$ times,then the probability that the head comes up an odd number of times is

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

Out of $21$ tickets marked with numbers from $1$ to $21$,three are drawn at random. The chance that the numbers on them are in $A.P.$ is

$A$ bag contains $12$ pairs of socks. If $4$ socks are picked up at random,the probability that there is at least one pair is equal to

Three faces of a fair die are yellow,two faces are red and one face is blue. If the die is tossed $3$ times,then the probability that the colours yellow,red and blue appear is (need not be in that order).

Two different families $A$ and $B$ are blessed with an equal number of children. There are $3$ tickets to be distributed amongst the children of these families so that no child gets more than one ticket. If the probability that all the tickets go to the children of family $B$ is $\frac{1}{12}$,then the number of children in each family is?