csatmedium
In a town, 45% population read magazine A, 55% read magazine B, 40% read magazine C, 30% read magazines A and B, 15% read magazines B and C, 25% read magazines A and C; and 10% read all the three magazines. What percentage do not read any magazine?
- A.10%
- B.15%
- C.20%
- D.25%
▶ Answer & Explanation
Correct answer: A. 10%
This problem involves set theory and can be solved using the principle of inclusion-exclusion or a Venn diagram. The formula for three sets is P(A U B U C) = P(A) + P(B) + P(C) - P(A ∩ B) - P(B ∩ C) - P(A ∩ C) + P(A ∩ B ∩ C). Plugging in the given percentages gives the total percentage of people who read at least one magazine. The percentage of people who do not read any magazine is then 100% minus this total.
Source: UPSC csat 2015