If $4\,P(A) = 6\,P(B) = 10\,P(A \cap B) = 1,$ then $P\left( \frac{B}{A} \right) = $

When two dice are thrown,what is the probability that the sum of the numbers appearing on them is $6$ or $7$?

The probability that a man will be alive $25$ years hence is $0.3$,and the probability that his wife will be alive $25$ years hence is $0.4$. Find the probability that $25$ years hence,only the woman will be alive.

From a pack of $52$ cards,$4$ cards are drawn. What is the probability that it has two digit-cards and one honours card of black suit and one honours card of red suit?

$4$ coins are tossed once. Find the probability of getting exactly $3$ tails.

$A$ committee consists of $9$ experts taken from three institutions $A, B$ and $C$,of which $2$ are from $A, 3$ from $B$ and $4$ from $C$. If three experts resign,then the probability that they belong to different institutions is