Question

You were to prepare a frequency distribution table regarding the blood groups of $30$ students of a class, Use this table to determine the probability that a student of this clss, selected at random, has blood group $AB$.

Answer 1

Total Number of students $=30$
Thus, sample space is given by, $n\left(S\right)=30$

Let $A$= event of having blood group of student as AB
Number of students having Blood group AB$=3$

$\therefore n\left(A\right)=3$
$\therefore P\left(A\right)=\frac{n\left(A\right)}{n\left(S\right)}=\frac{3}{30}=\frac{1}{10}$