$A$ purse contains $4$ copper coins and $3$ silver coins,the second purse contains $6$ copper coins and $2$ silver coins. If a coin is drawn out of any purse,then the probability that it is a copper coin is

If $A$ and $B$ are two independent events such that $P(A)=0.3$,$P(B)=x$ and $P(A \cup B)=0.44$,then $x=$

Two urns identical in appearance contain respectively $3$ green and $2$ black balls and $2$ green and $5$ black balls. One urn is selected at random and a ball is drawn from it. The probability that it is black is

One bag contains $5$ white and $4$ black balls. Another bag contains $7$ white and $9$ black balls. $A$ ball is transferred from the first bag to the second and then a ball is drawn from the second. The probability that the ball drawn is white,is

$A$ woman has $10$ keys,out of which only one opens a lock. She tries the keys one after another (keeping aside the failed ones) until she succeeds in opening the lock. What is the probability that the seventh key works?

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 . . . . . . .