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.

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 ball is either black or white.

When we toss a coin,there are two possible outcomes - Head or Tail. Therefore,the probability of each outcome is $\frac{1}{2}$. Justify your answer.

Two unbiased dice are thrown once. Write all the possible outcomes of this experiment. What is the probability that the sum of numbers on two dice is a factor of $18$?

Two balanced dice are rolled simultaneously. Then,the probability that the numbers on both the dice are prime is ...........

Apoorv throws two dice once and computes the product of the numbers appearing on the dice. Peehu throws one die and squares the number that appears on it. Who has the better chance of getting the number $36$? Why?