An experiment consists of recording the boy-girl composition of families with $2$ children. What is the sample space if we are interested in the number of girls in the family?

$A$ 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.

Three coins are tossed once. Find the probability of getting $3$ heads.

In a class of $60$ students, $30$ opted for $NCC$, $32$ opted for $NSS$, and $24$ opted for both $NCC$ and $NSS$. If one of these students is selected at random, find the probability that the student has opted for $NSS$ but not $NCC$.

When three coins are tossed simultaneously,what is the probability of getting a head on the first,a tail on the second,and a head on the third?

$A$ bag contains $4$ white,$5$ black and $6$ red balls. If a ball is drawn at random,then what is the probability that the drawn ball is either white or red?