Question

$\mu$ represents the set of students in class VIII and $n\left(\mu \right)=35$. $A$ is the set of students in the class VIII who have to wear spectacles and $n\left(A\right)=18$ State the value of $n\left(A^{\prime }\right)$.

Answer 1

$\mu \to$ the sets of students in class VIII

$A\to$ the sets of students in class VIII who have to wear spectacles

$A^{\prime }\to$ the sets of students in class VII who does not have a wear spectacles

$n\left(\mu \right)=35$

$n\left(A\right)=18$

No. of students who does not wear spectacles $=$ (no of students in class VIII)$-$ (no. of students who wear spectacles).

$n\left(A^{\prime }\right)=n\left(\mu \right)-n\left(A\right)$

$=35-18$

$=17$

$\therefore$ $n\left(A^{\prime }\right)=17$.