Q8 of 71 Page 30

The population of a town is 10000. Out of these 5400 persons read newspaper A and 4700 read newspaper B. 1500 persons read both the newspaper. Find the number of persons who do not read either of the two papers.

Let A denote the set of people who read newspaper A and B denote the set of people who read newspaper B.


Then, n(A) = 5400, n(B) = 4700, n(A ∩ B) = 1500, n(U) = 10000.


People who do not read either of the two papers are represented by (A ∪ B)’.


We have, n(A ∪ B) = n(A) + n(B) – n(A ∩ B)


n(A ∪ B) = 5400 + 4700 – 1500


n(A ∪ B) = 10100 – 1500 = 8600


n(A ∪ B)’ = n(U) – n(A ∪ B) = 10000 – 8600 = 1400


∴ Number of persons who do not read either of the two papers are 1400.


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If n(U) = 38, n(A) = 16, n(A ∩ B) = 12, n(B’) = 20, find n(A ∪ B).

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Let A and B be two finite sets such that n(A – B) = 30, n(A ∪ B) = 180. Find n(B).

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In a school, all the students play either Foot ball or Volley ball or both. 300 students play Foot ball, 270 students play Volley ball and 120 students play both games. Find

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