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Difficulty: 2/102023 NMTC 2023 (QII-53)

In group of 50 students 24 like cold drinks and 36 like hot drinks and each student likes at least one of the two drinks. How many like both coffee and tea?

Guide / Hint

Hint 1: Use the Principle of Inclusion-Exclusion: .

Hint 2: Substitute the given values: .

Hint 3: Solve for the intersection term.

Solution

Step 1 (Set up Set Formula): Let be the set of students who like cold drinks, and be the set of students who like hot drinks. We are given:

  • Total students (since each student likes at least one drink)

Step 2 (Apply Inclusion-Exclusion):

Step 3 (Conclusion): Exactly 10 students like both coffee and tea (both drinks).

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    2023 NMTC 2023 QII-53 - Olympiad Math Olympiad Question | Leminno