The probability of happening an event $A$ is $0.5$ and that of $B$ is $0.3$. If $A$ and $B$ are mutually exclusive events,then the probability of happening neither $A$ nor $B$ is

$A$ box contains $2$ black,$4$ white,and $3$ red balls. One ball is drawn at random from the box and kept aside. From the remaining balls in the box,another ball is drawn at random and kept aside the first. This process is repeated until all the balls are drawn from the box. The probability that the balls drawn are in the sequence of $2$ black,$4$ white,and $3$ red is

$3$ coins are tossed. Find the probability of getting at most $2$ heads.

$3$ coins are tossed. Find the probability of getting exactly $2$ heads.

The probability of getting head and tail alternately in three throws of a coin (or a throw of three coins) is:

In a box,there are $8$ red,$7$ blue and $6$ green balls. One ball is picked up at random. What is the probability that it is neither red nor green?