Given two mutually exclusive events $A$ and $B$ such that $P(A) = 0.45$ and $P(B) = 0.35,$ then $P(A \text{ or } B) =$

The probability that a student will succeed in the $IIT$ entrance test is $0.2$ and the probability that he will succeed in the Roorkee entrance test is $0.5$. If the probability that he will be successful at both places is $0.3$,then the probability that he does not succeed at either place is:

For two events $A$ and $B$,if $P(A \cup B) = 5/6$,$P(A^c) = 5/6$,and $P(B) = 2/3$,then $A$ and $B$ are

$A$ party of $23$ persons take their seats at a round table. The odds against two specific persons sitting together are

The probability that $A$ speaks the truth is $\frac{4}{5}$,while the probability that $B$ speaks the truth is $\frac{3}{4}$. What is the probability that they contradict each other when asked to speak on a fact?

The probabilities of occurrence of two events are respectively $0.21$ and $0.49$. The probability that both occur simultaneously is $0.16$. Then the probability that none of the two occurs is