Question

The number of students who had taken only Physics is :

• A. 2
• B. 3
• C. 5
• D. 6

Answer 1

The correct option is A 2

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

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

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

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

$n(M\cap P)=9$

$n(M\cap C)=5$

$n(P\cap C)=4$

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

AS we can see from the diagram

$n\left(Ponly\right)=n\left(P\right)-n(M\cap P)-n(P\cap C)+n(M\cap P\cap C)$

$n\left(Ponly\right)=12-9-4+3$

$n\left(Ponly\right)=2$