Three coins are tossed once. Find the probability of getting no head.

For two events $A$ and $B$,if $P(A \cup B) = \frac{5}{6}$,$P(A) = \frac{1}{6}$,and $P(B) = \frac{2}{3}$,then $A$ and $B$ are:

If a die is thrown $2$ times,what is the probability of getting $4$ at least once?

Two coins (a one rupee coin and a two rupee coin) are tossed once. Find the sample space.

$A$ bag contains $5$ black balls, $4$ white balls and $3$ red balls. If a ball is selected at random, the probability that it is a black or a red ball, is

$A$ box contains $10$ good articles and $6$ defective articles. One article is chosen at random. What is the probability that it is either good or defective?