Question

The number of students who had taken only two subjects is :

• A. 7
• B. 8
• C. 9
• D. 10

Answer 1

The correct option is C 9

Let the set of students who took maths, Physics and Chemistry be represented by M,P and C respectively.

$n\left(M\right)=15$

$n\left(P\right)=12$

$n\left(C\right)=11$

$n(M\cap P)=9$

$n(M\cap C)=5$

$n(P\cap C)=4$

$n(M\cap P\cap C)=3$

Let the no. of students who took only 2 subjects be $x$

$\Rightarrow x=n(M\cap C)+n(P\cap C)+n(M\cap P)-3n(M\cap P\cap C)$

$x=9+5+4-9=9$