$A$ bag contains $3$ white and $7$ red balls. If a ball is drawn at random,what is the probability that the drawn ball is either white or red?

In a simultaneous toss of $2$ coins,find the probability of getting exactly $1$ tail.

One ticket is selected at random from $100$ tickets numbered $00, 01, 02, \dots, 98, 99$. If $X$ and $Y$ denote the sum and the product of the digits on the tickets respectively,then $P(X = 9 | Y = 0)$ equals:

$A$ man speaks truth in $80 \%$ of the cases and another in $90 \%$ of the cases. While stating the same fact,what is the probability that they contradict each other?

$A$ box contains $4$ red balls,$5$ green balls and $6$ white balls. $A$ ball is drawn at random from the box. What is the probability that the ball drawn is either red or green?

If $P(A) = \frac{2}{3}$,$P(B) = \frac{4}{9}$ and $P(A \cap B) = \frac{14}{45}$,then find $P(A \cup B)$.