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
 Correct Answer: 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) $  Show Answer
  Answer:
Solution:
$ 20=n(P)+12-4\Rightarrow n(P)=12 $     Only Physics teacher = 8
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