Events $A$ and $B$ are independent events and $P(A)=P$,$P(B)=\frac{1}{2}$ and $P(A \cup B)=\frac{3}{5}$,then the value of $P$ is . . . . . . .

Two cards are drawn from a pack of well-shuffled $52$ playing cards one by one without replacement. The probability that both cards are queens is:

$A$ bag contains $16$ coins,of which $2$ are counterfeit with heads on both sides. The rest are fair coins. One coin is selected at random from the bag and tossed. The probability of getting a head is

Three cards are drawn successively,without replacement from a pack of $52$ well-shuffled cards. What is the probability that the first two cards are kings and the third card drawn is an ace?

$A$ bag $X$ contains $2$ white and $3$ black balls,and another bag $Y$ contains $4$ white and $2$ black balls. If one bag is selected at random and one ball is drawn from it,what is the probability that the ball is white?

$A$ bag $X$ contains $2$ white and $3$ black balls and another bag $Y$ contains $4$ white and $2$ black balls. One bag is selected at random and a ball is drawn from it. Then,the probability for the ball chosen to be white is: