For two events $A$ and $B$,$P(A)=0.5$,$P(A \cup B)=0.6$ and $P(B)=K$ are given. If $A$ and $B$ are independent events,then $K=$ . . . . . . .

If the probability of an event occurring is $3:8$,what is the probability of the event not occurring?

If the probabilities of a student passing in the first,second,or third grade are $1/10$,$3/5$,and $1/4$ respectively,then the probability of the student failing (getting a fourth grade) is ........

The odds against a certain event is $5 : 2$ and the odds in favour of another event is $6 : 5$. If both the events are independent,then the probability that at least one of the events will happen is

For an event,the odds against are $6 : 5$. The probability that the event does not occur is

If a number is selected from the first $30$ natural numbers, then the probability that the number selected is divisible by $4$ or $7$ is: