Question

$\begin{array}{cc}\text{Blood group}& \text{Number of students}\\ \text{A}& 9\\ \text{B}& 6\\ \text{AB}& 3\\ \text{O}& 12\\ \text{Total}& 30\end{array}$
The above frequency distribution table represents the blood groups of 30 students of a class. Use this table to determine the probability that a student of this class, selected at random, has blood group AB.

Answer 1

Total number of students = 30
Number of students having blood group AB= 3

$\text{P( students having blood group AB)}=\frac{\text{Number of students having blood group AB}}{\text{Total number of students}}$
Hence, required probability, $P=\frac{3}{30}=\frac{1}{10}$