$2$ boys and $2$ girls are in Room $X$, and $1$ boy and $3$ girls in Room $Y$. Specify the sample space for the experiment in which a room is selected and then a person.
Let us denote $2$ boys and $2$ girls in room $X$ as $B_{1}, \,B_{2}$ and $G_{1},$ and $G_{2}$ respectively. Let us denote $1$ boy and $3$ girls in room $Y$ as $B_{3},$ and $G_{3},\, G_{4}, \,G_{5}$ respectively.
Accordingly, the required sample space is given by
$S =\{X B_{1}, \,X B_{2},\, X G_{1},\, X G_{2}$, $Y B_{3},\, Y G_{3},\, Y G_{4}$, $Y G_{5}\}$
A bag contains $3$ red and $5$ black balls and a second bag contains $6$ red and $4$ black balls. A ball is drawn from each bag. The probability that one is red and other is black, is
A die is thrown, find the probability of following events: A number less than or equal to one will appear,
A die is thrown. Describe the following events : $A$ : a number less than $7.$ Find the $A \cup B$.
A bag contains $9$ discs of which $4$ are red, $3$ are blue and $2$ are yellow. The discs are similar in shape and size. A disc is drawn at random from the bag. Calculate the probability that it will be not blue,
The probabilities of a problem being solved by two students are $\frac{1}{2},\frac{1}{3}$. Then the probability of the problem being solved is