1.Set Theory
easy

$20$ 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 is

A

$12$

B

$8$

C

$16$

D

None of these

Solution

(a) Let $n\,(P)$= Number of teachers in Physics.

$n\,(M)$= Number of teachers in Maths

$n\,(P \cup M) = n(P) + n\,(M) – n\,(P \cap M)$

$20 = n\,(P) + 12 – 4$ ==> $n\,(P) = 12$.

Standard 11
Mathematics

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