If three smallest squares are chosen at random on a chess board,then the probability of getting them in such a way that they are all together in a row or in a column 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

From a pack of $52$ playing cards,three cards are drawn simultaneously. The probability that these are one king,one queen,and one jack is:

There are $8$ boys and $7$ girls in a classroom. If the names of all those children are written on paper slips and $3$ slips are drawn at random from them,then the probability of getting the names of one boy and two girls or one girl and two boys is

$A$ box contains $6$ black,$4$ red,$2$ white,and $3$ blue shirts. If $2$ shirts are picked at random,what is the probability that both are white or both are blue?

If a person throws $3$ dice,what is the probability that the sum of the numbers obtained is exactly $15$?