$A$ bag contains $9$ discs of which $4$ are red,$3$ are blue,and $2$ are yellow. The discs are similar in shape and size. $A$ disc is drawn at random from the bag. Calculate the probability that it will be either red or blue.

If any four numbers are selected,what is the probability that the last digit of their product will be $1, 3, 5$ or $7$?

Thirty-two persons $X_1, X_2, \ldots, X_{32}$ are randomly seated around a circular table at equal intervals. Two persons $X_i$ and $X_j$ are said to be within earshot of each other if there are at most three persons between them on the minor arc joining $X_i$ and $X_j$. The probability that $X_1$ and $X_3$ are within earshot of each other is:

In the following experiment,specify the appropriate sample space: $A$ person is noting down the number of accidents along a busy highway during a year.

In a competition,$A, B$,and $C$ are participating. The probability that $A$ wins is twice that of $B$,and the probability that $B$ wins is twice that of $C$. Then,the probability that $A$ loses is:

Let $E_1, E_2, E_3$ be three arbitrary events of a sample space $S$. Which of the following statements is correct?