$A$ coin is tossed twice. What is the probability that at least one tail occurs?

The probability of happening at least one of the events $A$ and $B$ is $0.6$. If the events $A$ and $B$ happen simultaneously with a probability of $0.2$,then $P(\bar{A}) + P(\bar{B}) = $

If $A$,$B$,and $C$ are mutually exclusive and exhaustive events of a sample space $S$ such that $P(B) = \frac{3}{2} P(A)$ and $P(C) = \frac{1}{2} P(B)$,then $P(A) = $

Three coins are tossed once. Find the probability of getting $3$ heads.

The probability of drawing a white ball from a bag containing $3$ black balls and $4$ white balls is:

$A$ bag contains $6$ white,$5$ black,and $4$ red balls. Find the probability of getting a white or a black ball when one ball is drawn from the bag.