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CA Foundation · Quantitative Aptitude · Sets, Relations and Functions, Limits and Continuity

In a survey of 100 customers of a Pune store, 60 buy tea, 45 buy coffee and 20 buy both. How many customers buy neither tea nor coffee?

15 customers buy neither. Using the union formula, those buying tea or coffee number 60 + 45 − 20 = 85. Subtracting this from the total of 100 customers leaves 15 who buy neither product.

  1. A15Correct
  2. B10
  3. C35
  4. D25

Explanation

n(T ∪ C) = 60 + 45 − 20 = 85. Customers buying neither = 100 − 85 = 15. Option 25 arises if one subtracts 60 from 100 and ignores coffee overlap incorrectly, and 35 arises from forgetting to add back the overlap (100 − 65).

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