If $A$ and $B$ are two events such that $P(A) = 0.4$,$P(A \cup B) = 0.7$ and $P(A \cap B) = 0.2$,then $P(B) = $

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

The probability that a leap year will have $53$ Fridays or $53$ Saturdays is

If the probability for $A$ to fail in an exam is $0.2$ and that for $B$ is $0.3$,then the probability that either $A$ or $B$ fails is $\leq \ldots \ldots$.

If the probability of $A$ failing an exam is $1/5$ and the probability of $B$ failing is $3/10$,what is the probability that either $A$ or $B$ fails?

$A$ card is drawn at random from a pack of $52$ cards. The probability of this card being a red card or a queen is: