The probability of choosing randomly a number $c$ from the set $\{1, 2, 3, \ldots, 9\}$ such that the quadratic equation $x^2 + 4x + c = 0$ has real roots is

In a single throw of two dice,what is the probability of getting a total of $13$?

Six faces of an unbiased die are numbered with $2, 3, 5, 7, 11$ and $13$. If two such dice are thrown, then the probability that the sum on the uppermost faces of the dice is an odd number is

If $X_1, X_2, \ldots, X_n$ are $n$ independent events such that $P(X_r) = \frac{1}{r+1}$ for $r = 1, 2, \ldots, n$,then the probability that none of the $n$ events occur is

In a single throw of a fair die,what is the probability of getting a number less than $7$?

Two players play the following game: $A$ writes $3, 5, 6$ on three different cards; $B$ writes $8, 9, 10$ on three different cards. Both draw randomly two cards from their collections. Then,$A$ computes the product of the two numbers he/she has drawn,and $B$ computes the sum of the two numbers he/she has drawn. The player getting the larger number wins. What is the probability that $A$ wins?