Question

In a medical examination of students of a class, the following blood groups are recorded.

Blood Group	$\mathrm{A}$	$\mathrm{AB}$	$\mathrm{B}$	$\mathrm{O}$
Number of students	$10$	$13$	$12$	$5$

A student is selected at random from the class. The probability that he/she has blood group$\mathrm{B}$, is

• A. $\frac{1}{4}$
• B. $\frac{13}{40}$
• C. $\frac{3}{10}$
• D. $\frac{1}{8}$

Answer 1

The correct option is C

$\frac{3}{10}$

Find the probability that he/she has a blood group$\mathrm{B}$.

Number of students having blood group $\mathrm{B}$ $=12$

Total number of students $=10+13+12+5$

$=40$

The probability of an event $A$ is given by

$P\left(A\right)=\frac{Numberoffavourableoutcome}{Totalnumberoffovourableoutcomes}$

Probability of selecting a student having a blood group $\mathrm{B}$ $=\frac{numberofstudentshavingBbloodgroup}{totalnumberofstudents}=\frac{12}{40}=\frac{3}{10}$

Hence, the correct option is (c)