$A$ card is drawn from a pack of $52$ cards. $A$ gambler bets that it is a spade or an ace. What are the odds against his winning this bet?

The probability of occurrence of an event $A$ is $1/2$ and that of $B$ is $3/10$. If $A$ and $B$ are mutually exclusive, then the probability of occurrence of neither $A$ nor $B$ is (in $/5$)

If $A$ and $B$ are two independent events,then $P(A \cup B) = $

Suppose that $A, B, C$ are events such that $P(A) = P(B) = P(C) = \frac{1}{4}$,$P(AB) = P(CB) = 0$,and $P(AC) = \frac{1}{8}$. Then find $P(A \cup B)$.

If the odds in favour of an event be $3 : 5$,then the probability of non-occurrence of the event is

The probability that a leap year selected at random contains either $53$ Sundays or $53$ Mondays is: