There are chits numbered $1$ to $20$ in a box. One chit is drawn at random. Find the probability that the number on the chit is a prime number.

$A$ die is thrown once. Find the probability of getting:
$(i)$ a prime number;
$(ii)$ a number lying between $2$ and $6$;
$(iii)$ an odd number.

Two balanced dice are rolled. Find the probability that the sum of numbers on two dice is odd.

There are $5$ white,$7$ red,$4$ black,and $2$ blue identical balls in a box. One ball is selected at random from the box. Find the probability that the selected ball is either white or blue.

$A$ card is drawn at random from a well-shuffled pack of $52$ cards. Find the probability that the card drawn is a queen.

An unbiased coin is tossed thrice. The probability of getting a tail all three times is ...........