Given $P(A \cup B)=0.6$ and $P(A \cap B)=0.2$,the probability that exactly one of the events occurs is:

Three coins are tossed once. Let $A$ denote the event 'three heads show',$B$ denote the event 'two heads and one tail show',$C$ denote the event 'three tails show',and $D$ denote the event 'a head shows on the first coin'. Which events are simple?

There are $3$ families,each having $1$ boy and $1$ girl. If one child is selected from each family,what are the elements of the event that only girls are selected?

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

$A$ 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 yellow. (in $/9$)

If $A, B,$ and $C$ can hit a target $4$ out of $5$ times,$3$ out of $4$ times,and $2$ out of $3$ times respectively,what is the probability that exactly two of them hit the target?