Two cards are drawn from a pack of $52$ cards. What is the probability that one of them is a queen and the other is an ace?

An urn contains $8$ red and $5$ white balls. Three balls are drawn at random. Then,the probability that balls of both colours are drawn is

From a group of $50$ students,two sections comprising of $20$ and $30$ students are formed. If $Ram$ and $Rahim$ are two particular students among the $50$ students,then the probability that they both belong to the same section is

If the coefficients $a$ and $b$ of a quadratic expression $x^2+ax+b$ are chosen from the sets $A=\{3, 4, 5\}$ and $B=\{1, 2, 3, 4\}$ respectively,then the probability that the equation $x^2+ax+b=0$ has real roots is

Four numbers are chosen at random (without replacement) from the set $\{1, 2, 3, ..., 20\}$.
Statement-$1$: The probability that the chosen numbers when arranged in some order will form an $A.P.$ is $\frac{1}{85}$.
Statement-$2$: If the four chosen numbers form an $A.P.$,then the set of all possible values of common difference is $\{\pm 1, \pm 2, \pm 3, \pm 4, \pm 5, \pm 6\}$.

If three dice are thrown simultaneously,then the probability of getting a score of $7$ is