In a school there are 20 teachers who teach Mathematics or Physics. Of – InterviewSolution

1.

In a school there are 20 teachers who teach Mathematics or Physics. Of these, 12 teach Mathematics and 4 teach both Physics and Mathematics. How many teach Physics?

Answer»

Let M = set of teachers who teach Mathematics

P = set of teachers who teach Physics

Then, n(M∪P) = 20, n(M) = 12, n(M∩P) = 4

n(P) = n(M∪P) + n(M∩P)- n(M)

= 20 + 4-12 = 12.

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