Sets-Relations-And-Functions Question 127

Question: 20 teachers of a school either teach mathematics or physics. 12 of them teach mathematics while 4 teach both the subjects. Then the number of teachers teaching physics only is

Options:

A) 12

B) 8

C) 16

D) None of these

Show Answer

Answer:

Correct Answer: B

Solution:

  • [b]Let n(P) = Number of teachers in physics $ n(M)= $
    Number of teachers in Maths $ n(P\cup M)=n(P)+n(M)-n(P\cap M) $
    $ 20=n(P)+12-4\Rightarrow n(P)=12 $ Only Physic?s teacher = 8